First and foremost this is an arena map. If the server is running with weapon stay on, then every player will spawn with a pulse rifle, making that the primary weapon on the map. Like all arena maps, all spawn points are within the arena, but Transitive Inversion has spawn tubes to provide you with an extra second to prepare for your arrival into the fray. This is enough time to have your pulse gun ready by the time your feet hit the ground. If the map is being run with nine or ten players this becomes very important, because if you don't frag right away you can bet you will be fragged yourself. With high player counts this is a very fast map.
Unlike most arena maps, though, Transitive Inversion has a basement. In the basement, which is heavily bottlenecked, you'll find a sniper rifle, a minigun, and a shieldbelt. Picking up the shieldbelt will drop you back into the arena, so be prepared.
And when things really heat up here, when the fragging is intense and fast enough, all hell will break loose. The arena opens up. New weapons come into play. And the word frantic gets redefined.