Anyone heard of or play(ed) OGame? Straight from the website...
OGame is a strategic space simulation game with thousands of players across the world competing with each other simultaneously. All you need to play is a standard web browser.
It's more strategical than graphical, since you basically click to upgrade your buildings, build ships and attack others. However, it ends up being really fun, espcially when you join forces with others to wipe a planet out. If you ever decide to play, join Universe 38! My ingame name is Axor.