How about a MMOAG? with 50 million players. Amazingly realistic, all actual tanks (pretty much). And its free, with the freemium model.
"The players in World of Tanks can choose four primary types of battles: random battles, team-training battles, tank-company battles, and clan battles.
There are three types of random battle; Standard, Assault and Encounter. Players have the option to be excluded from Assault and Encounter battles. All random battles consist of two teams of 15 randomly selected players on a randomly selected map.
The goal is to capture the enemy flag/base or eliminate all enemy tanks within 15 minutes. If time expires it is a draw.
An attacking team has to capture a defending team's base or eliminate all enemy tanks within 10 minutes. If time expires the defending team wins.
Two teams fight to capture a single neutral base or eliminate all enemy tanks within 15 minutes. If time expires it is a draw."