Alien Breed II · rebuilt for the browser
Alien Breed II: The Horror Continues (Team17, 1993), the whole game, rebuilt from the game's own 68000 code – not an emulator. The page contains no game data: insert your own Alien Breed II disk images (.adf, Amiga 500 version: disks 1 and 2, disk 3 for the later levels). Drop them here or choose them below; they stay in your browser.
Fire (Ctrl / Z or a gamepad button) skips the intro; on the title screen fire starts the game. Without a key the game plays its intro and then its own demo.
Arrows · Ctrl / Z = fire · M map · Space terminal · E Original / Enhanced · F fullscreen · P pause · H help
Help
Arrows or WASD: move. Ctrl / Z: fire. M: map. Space: Intex terminal. A gamepad works too (press a button first): stick / d-pad, A / B / X / right trigger = fire. Touch controls appear on phones and tablets.
Player 2: I J K L, right Shift / Enter = fire, or a second gamepad.
E: Original / Enhanced. F: fullscreen. P: pause. R: restart. H or ?: this help. Esc: close.
When the game asks for your name or a level code, type it on the keyboard: letters, digits, Backspace, Enter.
Enhanced shows more of the level around the original window (drawn from the level map). Both modes move smoothly at your monitor's refresh rate; the game itself still runs at 50 Hz. Display and Sound remember their settings separately for Original and Enhanced. Game → Continue from level offers the start of every level you have reached.
About this rebuild
Thanks for playing!
Alien Breed II: The Horror Continues (Team17, 1993) rebuilt for the browser from the game's own code: the 68000 code on your disks is statically translated to C and WebAssembly with the AREK kit, and the Amiga chipset (bus slots, Copper, Blitter, bitplanes, sprites, Paula) is a model checked against an emulator.
Measured against the original in an emulator (level 1, four 30-second runs with random joystick input): 99.9 % of the pixels match, the sound chip writes match in 97–100 % of the frames, and the game state matches tick by tick for the whole run in one of the four – in the others small CPU timing differences make the runs drift apart after 1–3 seconds. Enhanced draws a wider view from the level map and the game's own drawing, and moves smoothly at your display's rate.
After Start the game boots as it did from floppies: its intro, title, hall of fame and credits take about 1½ minutes and end in a demo that plays itself. Fire (Ctrl / Z or a gamepad button) skips the intro; on the title screen fire starts the game, and level 1 is reached in about 25 seconds.
On the way we found two bugs in the original game: explosion debris can fly through a wall and off the map (the game then reads memory outside the map – harmless on an Amiga), and the sound driver can mix up a sound number (a leftover high byte), which silences a channel. Both are handled without changing how the original plays.
The page contains no game data. The translated code and the start state are encrypted and only your own disks unlock them; the disk images never leave your computer.
Built with the AREK kit.