This game is nuts
Steam says I've played it for 710 hours now. Versus Mode is where it's at, but if you want even more fun, join a gaming community like ZCC on Steam and you get an option to join their servers from the main screen. They run stuff like 10v10 versus with extra bells and whistles, like earning money ("caps") with which you can buy perks and boons for yourself and your team.
The ZCC mod is the most advanced out there, but you can find similar ones on other servers. The common element is that you have 10 players per side and things get really intense that way. Highly recommended