Tremulous (and forks)
An asymmetric multiplayer game where you can either play as an alien or a soldier hunting the alien. Forks are Tremfusion and Unvanquished, with unvanquished being the most modern of the three. Tactical but not quite in the way I’m looking for
Wolfenstein:Enemy Territory and ET:Legacy
ET Legacy is a client for ET, and it brings modern features to it. Both are pretty fast paced and not very tactical.
Übergame
It looks pretty good for a libre game, and looks to play good too. About as tactical as ET.