netPanzer is an open source online multiplayer tactical warfare game.

netPanzer is an online multiplayer tactical warfare game designed for FAST ACTION combat. Gameplay concentrates on the core, no resource management is needed. The game is based on quick tactical action and unit management in real-time. Battles progress quickly and constantly as destroyed players respawn with a set of new units. Players can join or leave multiplayer games at any time. Official netPanzer development got basically halted in 1999, since 2002 netPanzer is available under the GNU GPL and thus Free Software and a GNU/Linux port of netPanzer is ready. netPanzer is a game designed to fit into the real-time tactical game genre. It’s art is based on realistic environments and vehicles. Battle will heat up as players challenge for territory, and without the need for resource management battles will emerge swiftly.

–Support from 1 to 100 players over the Internet or on LAN systems depending on the network connection type and game configuration (single/multi dedicated server vs. server-player, max number of units per player and so forth).

Link to Official Site (to find your linux distro and to find game servers)