When was the Half-Life first-person shooter game released by game development community MapCore? 
MapCore: MapCore is a game development community with origins in "Half-Life" mod production, which since its inception in 1999 has evolved into a thriving forum featuring all flavours of game development including level design, modelling, concept art, and programming. Half-Life (video game): Half-Life (stylized as HλLF-LIFE) is a science fiction first-person shooter video game developed by Valve, released in 1998 by Sierra Studios for Microsoft Windows.
1998