Most of the non-client stuff in PCRPG 4 has been inserted into 3.x. PCRPG 4 was the old version of PCRPG that UG was going to head up (never did anything, only I did). Some examples are the EXP system, unique bot names, news, and other similar things. Deus created the required item system to allow for the item diversity, but it crashed OpenGL clients. Shorty after that, Deus exited the scene after I punished his little brother for in-game violations. I refused to back down just because he was Deus's brother. Because of that, he left before the item system was debugged entirely. Other than that, PCRPG 5 is the old name for what is today PCRPG on the Source engine.