I was wondering if this game can support 3+ players, because I can't see a strategy game I like if I can only play games of fighting one person.

no this is purely 1v1.

MA is not your typical game It breaks many traditional barriers that have made so many games just clones of each other. Yes, it is a 1v1 game, but in this case it very much makes sense. We have just started a clan war, however, that makes teamwork more possible. The actual games are 1v1 still, but the overall clan strategy requires good team work.

In general, I'd say that you should try this game out, even if it doesn't have a specific feature you usually look for. My bet is that you'll find that this game has an unsurpassed depth and replayability, and has a design that can't be beat.

Some reasons behind only allowing 1v1 play can be found in these posts:
http://massiveassault.com/forum/viewtopic.php?t=166
http://massiveassault.com/forum/viewtopic.php?t=253