It isn't. It isn't entirely GPP. In fact it's still more 1.1-sided. For example, I didn't apply the fix where melee weapons can hit walls, so aliens can't bite through cages like they do in gpp. Tyrant trample is more of a knockback-punt-ing weapon rather than a lawn mower. Dragoon pounce punts more rather than damage dealing. Blaster is used for movement (except it is nullified when grabbed by a basi) a bit like xonotic's laser. Lcannon are dynamic. There's vampire mode (votable). There's FreeforAll/Teamkill mode (votable). There's physics support for other games (not completed, but done to an extent for some i.e. Team Fortress Classic). Comes with bots that interact with you (says stuff like "You suck!" after dominating you, or will use /teamstatus occasionally) and has reaction time based on their ping, and has ping-based aiming, has the ability to aim ahead (it's more fun when they do airshots with luci, lol) while some stuff were removed like acid gun (OP with jetpack, lol! Just pour all over the bugs below, they can't do a thing!) and tyrant spitbombs because they were just-for-fun, but bend the gameplay too much.
