Open-source alternatives to Openspades

Aleph One is the open source continuation of Bungie’s Marathon 2 game engine.

This is an in-progress modern open-source engine for the 1994 DOS game The Elder Scrolls: Arena by Bethesda Softworks. The goal is to replicate all aspects of the original game with a clean-room approach while making quality-of-life changes along the way. Details on Arena's inner-workings can be…

portable, enhanced runescape classic client ported to C99. supports 204 and 177 protocols. original mudclient204 java source refactored by v0rtex/xetr0v and Isaac Eggsampler. compatible with rscsundae, openrsc and 2003scape.

Mindustry is a cross-platform game engine and factory automation simulation that combines resource management with tower defense strategy. Players construct complex supply chains and automated networks to process materials while building defensive structures to protect a core from waves of hostile mechanical forces. The project utilizes a deterministic lockstep networking model to ensure simulation consistency across desktop and mobile devices. It is built on an entity-component-system architecture and a tile-based grid simulation, allowing for the efficient management of thousands of active

High-performance QuakeSpasm fork

Zelda Classic is a game and editing tool that lets you create custom Legend of Zelda quests.

CatacombGL is a source port with OpenGL graphics for Catacomb 3D (1991), The Catacomb Abyss (1992), The Catacomb Armageddon (1992) and The Catacomb Apocalypse (1993).

Cross-platform port of Arx Fatalis, a first-person role-playing game

AssaultCube

Abyss Engine clean-room reimplementation of Diablo 2, written in C. The goal is to recreate the original game engine, but on a portable platform that can also easily be modded and extended.

Fork of inolen/quakejs with additonal content server, local play page, and start-stop script

A high-fidelity reimplementation of Crimsonland v1.9.93 (2003, GOG "Crimsonland Classic") in Python raylib, paired with deep reverse engineering of the original Windows binary.

OpenJazz is a free, open-source version of the classic Jazz Jackrabbit™ games.

Unofficial source port for Blake Stone series

DOOM Retro is the classic, refined DOOM source port for Windows PC. It represents how I like my DOOM to be today, in all its dark and gritty, unapologetically pixelated glory. I have strived to craft a unique and cohesive set of compelling features, while continuing to uphold my respect for that…

ClassiCube is a custom Minecraft Classic compatible client written in C from scratch. ClassiCube is not affiliated with (or supported by) Mojang AB, Minecraft, or Microsoft in any way. ClassiCube is not trying to replicate modern Minecraft. It will never support survival, Minecraft accounts, or…

This game is a clone of Wordle. It's like the MasterMind game), but instead of colors you have to guess words.

This is open source Grand Theft Auto 1 remake project.

GZDoom is a feature centric port for all Doom engine games, based on ZDoom, adding an OpenGL renderer and powerful scripting capabilities

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Open Source role-playing game engine for Taleworlds' Mount&Blade Series written in C# using Ogre3d Engine.

A remake of the 1995 RPG Albion

Classic overhead run-and-gun game

Banjo: Recompiled is a project that uses N64: Recompiled to statically recompile Banjo-Kazooie into a native port with many new features, enhancements, and extensive mod support. This project uses RT64 as the rendering engine to provide graphical enhancements.