VGA Planets is a popular and long running turn based space strategy game. It was created in 1991 and became the most popular play by email game ever created. Planets Nu is the new online browser based version designed as a fun and active social network.
It is free to play and requires no additional software or downloads.

Space Strategy Game

VGA Planets is a turn based space strategy game. Each game takes several months to play and involves between 2 and 30 players. Planets offers meaningful logistics and meaningful intelligence and is considered a zero-sum game. This is an important strategic difference from many strategy games. In that the limitation of key units (ships) is spread accross all players. This means strategies of just attacking and sacrificing ships and winning through shear economic might do not work. Economy does play a huge role, however because of the ship limit it may not be possible to replace a ship after it has been destroyed. Even if you have the resources. You must win tactical battles that provide an advantageous outcome in order to win more opportunities to build ships.