IMO Quake 1 was the pinnacle of moddable ID engines. This because it used its own language, quake-c, and a simple compiler. Beyond that there were few inherent

IMO Quake 1 was the pinnacle of moddable ID engines. This because it used its own language, quake-c, and a simple compiler. Beyond that there were few inherent limits to the engine, so people set of making wild weapon packs (some having up around 20 guns that could have multiple modes), RPGs (abusing the hell out of how the game transferred character state between maps), even simple flight sims and driving games. Come Quake2 you needed VC++ to do mods (leading to a way fewer single developer experimental mods), and come Quake3 there was a hard cap on the number of weapons the mod could contain.