Spring is an rts based on the game Total Annihilation. Its all free to download and play, and the community is growing - 250 players online on a good evening.
On the Spring client there are many differnet mods played, the most popular being Balanced Annihilation which I play (about 75% of games play this mod). I've played it for about a year but im posting about it now as an integrated ladder has just been added to the client, similar to iccup where games are auto-reported when its over. It's also not one of those rts with no micro/macro. It requires lots of strategy along with micro!

http://spring.clan-sy.com/download.php - to download Spring
http://www.spring-league.com/ - The Ladder (A work in progress, but still works great)
http://spring.unknown-files.net/file/3582/Balanced_Annihilation_5.71/ - download link for Balanced Annihilation, the most popular mod. After downloading save to Spring/mods
Iv'e not covered lots so ask any questions you want
