Hexwaste

A C# / .NET + MonoGame (DesktopGL) re-implementation of a slice of the Fallout 2 engine: it loads the original data files and gives you a living world — real maps, real scripts, dialog, looting, a persistent world across map travel, save/load, and turn-based unarmed combat where the wasteland fights back.

Requires an original copy of Fallout 2 (GOG/Steam). No game assets are included or distributed. "Fallout" is a trademark of Bethesda Softworks; this project is not affiliated with or endorsed by Bethesda and names the game only to describe interoperability with your own legally obtained data.

Quick start

dotnet run --project src/Hexwaste.Viewer -- --game-dir "/path/to/Fallout 2"

The game directory is the install folder containing master.dat, critter.dat and patch000.dat. Without --game-dir, Hexwaste probes the usual GOG/Steam install paths and a game-data/ folder next to the executable.

Latest release: v0.14.0 — Interplay MVE video support — the engine's cutscenes now decode and play in-engine. Prebuilt self-contained builds (Linux x64 / Windows x64) are on the releases page; see docs/RELEASING.md to build your own.

What works

• World: DAT2 archives, FRM sprites + palette cycling, AAF fonts, full static lighting (light pools, day/night clock, script-set ambient — caves dim to their cavern level on entry), roofs/egg transparency, sound (a C# port of the Interplay ACM decoder — music, sfx, footsteps, with positional attenuation: off-screen sounds fade with distance vs your Perception), ambient NPC life (fidgets, wander, script-driven brahmin behavior).
• Scripts: a micro INT-bytecode VM with a real script host — map-entry scripts lock doors and stock containers, examine/dialog/lockpick/timer procedures run for real, script timers fire (doors auto-close behind you).
• Dialog: full gsay conversation trees with keyboard choices, and the iconic Fallout 2 animated talking head above the reply (the real per-NPC head art, idling on its fidget animation) whenever a script supplies one — and the head reacts: script mood nudges shift it between its good/neutral/bad animation families with the proper transition, and voiced lines lip-sync with the matching phoneme set.
• Persistent world: per-map deltas keyed to the pristine map files — loot a footlocker in the Den, walk to the Temple and back, it stays looted; F5/F9 saves the whole visited world as JSON.
• Combat: turn-based fights with engine-accurate sequencing (outcome rolled before the animation, damage applied when it completes) and initiative-ordered turns (every combatant interleaved by their Sequence stat each round — a faster foe acts before you), AP budgets, melee weapons and armor (equip flags straight from the MAP files — enemies use their own spears), healing items, death falls (a hefty burst, laser, or explosion leaves a suitably gory corpse) and lootable corpses that stay dead across map travel, AI turns, same-team joiners, and script-driven aggro — temple ants jump you on sight. Enemies read their ai.txt packets: they close to a viable shot, flee when badly wounded, draw a carried backup weapon (per their packet's weapon preference) when their gun runs dry, and — if they're the type that carries chems — gulp a stimpak mid-fight when you've hurt them, instead of fighting to the last hit point. Critical hits (from in-game day 2, like the engine) roll off the real Fallout 2 crit tables — bonus damage, armor bypass, the occasional instant kill; press V for the called-shot dialog and click a body part — eyes/head/legs — to trade accuracy for a far better critical. And criticals have consequences (the engine's massive-critical roll): a blow can blind, cripple a limb, knock a target out cold (it wakes after a spell), or cost it a turn — a blinded foe fights at −25, and the Skilldex Doctor skill mends limbs and eyes. Misses can backfire too: a critical FAILURE makes a fighter fumble — lose the turn, drop or wreck the weapon, hurt itself, even wing a bystander (your own fumbles only bite once you're a seasoned wastelander — day 6, like the engine). Moving in combat costs action points per hex (you can't free-walk the map mid- fight), a crippled leg costs 4× so it crawls, and a crippled arm blocks a two-handed weapon (both arms block any weapon). Action points you don't spend aren't wasted: leftover AP harden you into a temporary dodge — every unspent point adds to your Armor Class until your next turn, so a fighter who blows everything attacking is easy to hit, while one who holds back is slippery (an unarmed brawler with Hand-to-Hand Evade dodges twice as hard). Big melee blows knock the target sprawling back along the hex line; a crit leaves it prone (+40 to hit, 3 AP to stand). Throw a spear or rock (Throwing skill, range scaled by Strength) — it lands recoverable on the ground — or lob a grenade for an area blast with falloff and knockback. With a burst gun (10mm SMG, Tommy Gun, combat shotgun) hold the trigger (B): the magazine sprays a cone of rounds — in a duel a few find the target and the rest chew up the scenery, the same spread the engine rolls. You choose what to load: unload (Shift+R) and use another ammo box to switch between, say, armor-piercing and hollow-point — AP punches through a foe's armor, JHP doubles the damage to an unarmored one. Every blow floats its damage over the target — a red number for a hit (a lighter shade when it's you taking it), yellow for a critical, a white "Missed" for a whiff — rising and fading above the struck critter (the real Fallout 2 prints combat results to the message log; Hexwaste floats them too, reusing the engine's own text-object timing, placement and colours). Sneak (the Skilldex Sneak skill toggles it): a periodic skill roll decides whether you're really hidden, and while you are an NPC's perception range shrinks — sneak wide around a foe and its scripted aggro never fires; with the Silent Death perk a melee strike from behind hits for 4×. Chems give a temporary edge — Buffout, Jet and the like boost your SPECIAL stats for a while, then wear off through a comedown that leaves you briefly weaker before it settles back — but lean on them and you can get addicted: after a while withdrawal saps the matching stats until it passes (Jet's is permanent without the antidote). Kills pay XP at combat end and are tallied by type on your character sheet; levels raise your HP. The game difficulty (--difficulty easy|normal|hard) scales how hard the wasteland hits back — on Easy everything not on your team deals 75% damage, on Hard 125% (the engine's combat-difficulty modifier; your own and your companions' blows are untouched). Lose, and F9 puts you back.
• Game shell: the authentic Fallout 2 front door — the real mainmenu.frm main menu (mouse + keyboard), the pickchar.frm premade selector (portrait, SPECIAL, bio), the edtrcrte.frm character-creation editor (point-buy SPECIAL with steppers, skill tagging, optional traits, a stat/skill description card, and the name/age/sex plates with their pop-up editors — type a name, spin the age 16–35), a scrolling credits.txt roll, and the iconic death.frm death screen when you fall.
• Cutscenes: the story movies play as real video — a from-scratch Interplay MVE decoder (the full _nfPkDecomp block codec plus Interplay DPCM audio, ported from fallout2-ce and validated pixel-exact against ffmpeg across all 13 game cutscenes) plays them full-screen with sound when a script calls play_gmovie (the intro, the temple-guardian dream, the endings), and F10 opens a browser to preview any cutscene in your game data.
• Character: create your own (name, age, SPECIAL, gender, optional traits, tagged skills) in the authentic creation editor, or pick a premade from the selector; level-ups grant skill points you spend on the character sheet (C), and stat-gated dialog runs the right branches — including IQ-gated options, so a low-Intelligence character gets the dumb lines and a bright one the smart ones. Skill books (Guns and Bullets, Scout Handbook…) raise their skill when read, with diminishing returns up to 100 — and a smarter character reads them faster. Rest (Z) heals over time. The character sheet and Pip-Boy show your karma and reputation — a reputation title (genrep.txt), per-town standings (Vilified… Idolized) and earned karma titles, read straight from the engine's stats/GVARs (the engine never auto-awards karma, so on this slice it stays neutral unless a quest sets it).
• Traits & perks: the 16 optional traits do real things (Gifted, Bruiser, Heavy Handed, Good Natured, One Hander, Fast Shot, Finesse, Jinxed…) — chosen at character creation or baked into a premade, and they feed combat (to-hit, AP, damage, criticals) and your per-level skill points (Educated, Skilled, Gifted). You pick a perk every 3 levels (G on the character sheet) from the ones you qualify for — Toughness, Action Boy, Sniper, Bonus Rate of Fire, Lifegiver and more, shown on the sheet with your traits.
• Encumbrance: items have weight, and your Strength sets a carry limit (shown on the inventory panel and Pip-Boy, red when you're over). Overload and you can't pick up / loot / buy more, and you lose action points in combat.
• Barter: real shopkeeper trade (Tubby's stock box and all) at the engine's price formula.
• Worldmap: the authentic worldmap window — the real chrome frame around a scrolling 1:1 map view (arrow keys / wheel / hover the edge), city circles with the "you are here" hotspot and destination markers, the alphabetical town-tab rail with red quick-travel buttons, the date/time readout, the day/night dial that turns with the clock, and the Vault-Tec globe plate. Click a discovered city (or its tab) to travel — the party marker crosses the view, paced by terrain: crossing mountains genuinely costs more game time (and car fuel) per pixel, exactly like the original's walk loop. The trip can be saved/resumed mid-walk. The TOWN/WORLD switch (or clicking the town you're standing in) flips to the townmap sub-view — the city's own map art with flashing entrance hotspots; pick one to walk in at that district. Driving the Highwayman swaps the globe for the animated car monitor with its draining fuel bar, and the car itself sits parked on the town map where you left it — click it to open the trunk. The map is fogged: subtiles you haven't been near stay black, ones you've glimpsed are dimmed, and the corridors you've walked are clear — and hidden sub-areas (Car Outta Gas, the toxic caves) only put a marker on the map once you've explored near them. The wasteland bites — travel rolls random encounters (worldmap.txt tables) and drops you onto a transient encounter map with the named group spawned in formation (rats, scorpions, war parties, slavers). A high Outdoorsman spots the encounter ahead and offers a Yes/No to avoid it (for XP); walk off the edge and travel auto-resumes toward your destination. An X-FIGHTING-Y encounter spawns its two groups on opposing teams so you stumble into a brawl already in progress — watch them thin each other out, or wade in.
• Locations: the opening hour (Arroyo → Temple → Klamath → Den) plus Vault City, Gecko, Modoc, Broken Hills, New Reno, NCR, San Francisco, Redding, and Vault 15 — the first nine towns past the slice. Travel there from the worldmap and every map (VC: Courtyard / Downtown / Council / Vault; Gecko: Settlement / Power Plant / Junkyard / Tunnels; Modoc: Main Street / Inn / Well / Outhouse; Broken Hills: the two town halves + desert/mountain sub-maps; New Reno: the four strip maps + interiors / boxing arena / chop shop / stables / casinos, 11 in all; NCR: Bazaar / Downtown / Council / entrance + courthouse; San Francisco: the Shi Chinatown / docks / Hubologist base / the PMV Valdez tanker / shuttle; Redding: Downtown
  • tunnels + the Kokoweef and Wanamingo mines; Vault 15: the squatter camp + entrances + the deep original-vault levels) loads, walks, and transitions; every external their scripts fire is wired, and their NPCs talk via the real dialogue VM. A new town is mostly content: the data-driven engine routes, loads, and renders it for free — the per-town work is just wiring the handful of script externals it needs (the --smoke <map> dev command scopes them), and each town makes the next cheaper (Gecko needed no new externals; Modoc four; Broken Hills' town none; New Reno, the biggest, five; NCR, San Francisco, Redding, and Vault 15 none — the wired set now covers them outright; the Sierra Army Depot robot dungeon needed two, the Mariposa Military Base super-mutant dungeon none, Navarro the Enclave base none, the Enclave Oil Rig endgame none) — the entire original-game map set now loads, walks, and runs its scripts. Quest machinery is in place — Vault City's citizenship test, Gecko's reactor terminal, Lenny's / Marcus's / Myron's / the Vault 15 Doc's / Sierra's Skynet recruitment (real party.txt companions), and Modoc's "Jonny in the Well" dialogue + scripted well; finishing a specific quest is content navigation, not engine work. A static bytecode census over all 1263 shipped scripts verifies 107 of the 110 Pip-Boy quests are completable end to end — the other three are the original game's own content bugs (their quest variables are never written to the completion value by any script), faithfully reproduced and pinned by a test.
• Companions: recruit, then a control hub (talk to them) — wait here / follow / trade / dismiss / rejoin; a 1:1 flat item trade to gear them up; and a combat-control window (the authentic CONTROL.frm art) to set their tactics (aggressive/defensive disposition, who to target, when to flee, how close to stay, when to burst-fire, which weapon to favour) — which the ally AI obeys.
• HUD: the authentic Fallout 2 interface bar (iface.frm) along the bottom — the green message monitor (a 100-line scroll-back history — click its top/bottom halves to page through it), the equipped-weapon slot with its attack-mode label, lit action-point pips, the HP/AC readout in the original digit font, the END TURN / END COMBAT buttons during a fight, and clickable INV/OPT/MAP/CHA/SKILLDEX/PIP tabs (the keyboard shortcuts still work). The SKILLDEX tab opens the use-skill picker — choose a skill (Lockpick, First Aid, Doctor, Steal, Traps, Science, Repair, Sneak) and click a target to apply it. The PIP tab opens the Pip-Boy: a status page (the real Fallout 2 calendar date, level, HP/AC, an embedded mini-map) and a rest menu (timed rests or rest-until-healed); press A for the full-window automap, which reveals as you explore (fog-of-war). The OPT tab (or Esc) opens the options/pause menu: save, load, main menu, quit, resume — and the 10-slot save/load picker renders its authentic LSGAME.frm window. The inventory (INVBOX.frm paperdoll), container looting (loot.frm), merchant barter (barter.frm) and companion trade (trade.frm) all render on their real Fallout 2 window chrome. Every panel and menu is fully mouse-navigable — click a row in the inventory/loot/barter/ trade lists (PgUp/PgDn page past the 9th item) or in the Pip-Boy/Options menus; the keyboard shortcuts still work alongside. The called-shot picker is the real body-diagram window — the target's wireframe called-shot portrait with per-species part names and the live to-hit % rendered in the original digit bezels — and elevators open their authentic per-location panel art with the animated floor gauge sweeping during the ride. With the Empathy perk your dialogue options are tinted by the NPC's reaction. Maps fade in from black as you travel between them.

Controls

Input	Action
mouse drag / arrow keys	pan (hold Shift for fast)
mouse wheel	zoom the world 1×–4× (integer magnify; the HUD stays native)
click open ground	walk there (A* on the hex grid)
click door / container / item / stairs	use / loot (click a row or 1–9 take, A take all) / pick up / travel
click a critter	talk (real scripted dialog, 1–9 to choose; shopkeepers open a barter panel)
right-click	examine (critters show HP/AC)
F	attack the hovered critter (starts combat)
B	spray a burst at the hovered critter (needs a burst gun: SMG/Tommy/combat shotgun)
V	open the called-shot dialog (click a body part to aim)
Space	end combat turn
L	lockpick the hovered door (the Skilldex Lockpick skill)
S	Skilldex — pick a skill (1–8), then click a target to use it
P	Pip-Boy — status page, rest (R for the rest menu, 1–9 pick a duration), and the Archives quest log
I	inventory (drag an item onto the weapon/armor slot to equip, or click / 1–9 use/equip/consume, Shift+1–9 drop)
C / K	character sheet (spend level-up skill points)
Z	rest to heal (when no enemies are near)
F5 / F9	quicksave / quickload (default slot)
F10	cutscene browser — preview any MVE movie in your game data (↑/↓ or hover, Enter/click to play)
R / Shift+R	reload the equipped gun (2 AP in combat) / unload it (to switch ammo type)
F4 / T / PgUp / PgDn	roofs / walk-cycle / elevation (PgUp/PgDn page an open item panel)
[ / ]	ambient light (night ↔ day)
M	worldmap
Esc	options / pause menu (save / load → a 10-slot picker / main menu / quit / resume)

A large set of --flags exists for headless testing (screenshots, scripted dialog/combat transcripts, deterministic RNG); see src/Hexwaste.Viewer/Program.cs.

Building & testing

dotnet build          # .NET 10 SDK
dotnet test           # set FALLOUT2_DIR=/path/to/game for the data-backed tests

# Golden regression nets — deterministic headless transcripts diffed against
# committed fixtures (need a display + your game data). Run after touching
# combat or worldmap/encounter code:
scripts/combat-golden.sh      # combat transcripts (check | record)
scripts/encounter-golden.sh   # worldmap / encounter / companion / panel state lines
scripts/quest-golden.sh       # original-game quests driven to completion (state-only)

The data-backed unit tests skip cleanly when FALLOUT2_DIR is unset, so a plain dotnet test passes without any game assets.

scripts/quest-golden.sh drives original-game quests to completion through the real script logic (dialogue VM + set_global_var, no faking) and locks each as a state-only golden. The per-town recipes and mechanics behind them live in docs/qa-sweep/ — the campaign quest-QA sweep notes.

Layout

• src/Hexwaste.Formats — engine + format code (DAT2/FRM/PAL/MAP/PRO/INT VM, script host, combat math, save model); no MonoGame dependencies, fully testable headless
• src/Hexwaste.Viewer — the MonoGame DesktopGL front end
• tools/ — CLI dump/debug tools (DatDump, FrmDump, MapDump)
• tests/ — xUnit suite
• docs/ — provenance: the research reports and prompts that drove each phase, RELEASING.md, and qa-sweep/ (the campaign quest-QA town notes)

License & attribution

Hexwaste is a modified derivative of fallout2-ce (the reverse-engineered engine re-implementation); ported routines carry // ported from fallout2-ce ... comments. It is licensed under the Sustainable Use License v1.0 (LICENSE.md, NOTICE.md): free of charge, non-commercial use and distribution only.