Amoebax 0.2.1 — ArcaOS/OS2 Port

Amoebax is a free, cross-platform Puyo-Puyo style puzzle game. Drop pairs of coloured amoebas onto a grid and chain groups of four or more of the same colour to clear them. Chains send garbage amoebas to your opponent's grid.

• Original game: Emma's Software (Jordi Fita)
• ArcaOS/OS2 SDL2 port: Martin Iturbide
• License: GNU General Public License v2 or later

---

Requirements

Component	Notes
ArcaOS 5.0+	(or eComStation 2.x with DIVE support)
SDL2.dll	SDL2 for OS/2
SDL2_image.dll	SDL2_image for OS/2
SDL2_mixer.dll	SDL2_mixer for OS/2

The SDL2 DLLs must be on the LIBPATH or in the same directory as amoebax.exe.

---

Installation

Extract the archive so the layout is:

amoebax.exe
amoebax.def
data\
    fonts\
    graphics\
    music\
    sfx\

Run amoebax.exe from a command prompt or double-click it.

---

Controls

Player 1 — left side

Key	Action
A	Move left
D	Move right
S	Push down
W	Rotate clockwise
Left Ctrl	Rotate counter-clockwise

Player 2 / Human (Normal mode) — right side

Key	Action
Left Arrow	Move left
Right Arrow	Move right
Down Arrow	Push down
Up Arrow	Rotate clockwise
Right Ctrl	Rotate counter-clockwise

Global

Key	Action
Alt+Enter	Toggle fullscreen / windowed
Escape	Pause

---

Building from Source

Requirements: GCC 9.2 / kLIBC (ArcaOS), GNU Make, SDL2 development headers.

compile-amoebax.cmd

The script sets EMXOMFLD_TYPE, EMXOMFLD_LINKER, and EMXOMFLD_PRELINK, then runs make -f Makefile.os2 inside src\. The build log is written to src\compile-amoebax.log.

---

Port Notes

This port migrates the original SDL 1.2 codebase to SDL2 and replaces the autotools build with a hand-crafted Makefile.os2.

Key SDL1 to SDL2 changes

• Fullscreen: SDL_WINDOW_FULLSCREEN_DESKTOP + virtual back buffer. SDL_BlitScaled centres and letterboxes the 800x600 game surface onto the desktop-resolution window, so the content is always correctly positioned.
• Alpha blending: SDL_SetAlpha replaced with SDL_SetSurfaceAlphaMod + SDL_SetSurfaceBlendMode(SDL_BLENDMODE_BLEND).
• Surface format: SDL_DisplayFormatAlpha replaced with SDL_ConvertSurfaceFormat(..., SDL_PIXELFORMAT_ARGB8888, 0).
• Window events: SDL_ACTIVEEVENT replaced with SDL_WINDOWEVENT_MINIMIZED (pause on minimise only, matching the original SDL1 behaviour).
• Unicode input: SDL_EnableUNICODE replaced with SDL_StartTextInput / SDL_TEXTINPUT event.
• Right-grid clip rect: Fixed a latent SDL1-era bug where the clip rectangle width used getGridPositionY() instead of getGridPositionX(), making the human player's falling pieces invisible under SDL2.