Mechwarrior: Living Legends is likely the best mechwarrior "game" yet released. I put game in quotes because MWLL is actually a mod for the game crysis wars, but i'll be damned if you remember this fact while playing. Unlike other MechWarrior games, MWLL is combined arms and brings battle armor, tanks, wheeled vehicles, vtols, aerospace, and hovercraft all onto the same battlefield as mechs. It also brings in many new mechanics like damage offload time for lasers and real projectiles for ballistic weapons(this is all compared to the ages old mechwarrior 4). It won first place for mod of the year when it was released, and has since then been the user selected honorable mention every year (cant win twice). If you're a fan of mech games you need to give this a try.
Heres some promo video links for the purpose of promo
http://www.youtube.com/watch?v=wROmf0d65A4http://www.youtube.com/watch?v=70yNAwUUsc0https://www.youtube.com/watch?v=lNFeE8mIlxQTo top it off they just released version 0.6.0, probably the biggest single release yet with 2 aerospace, 5 mechs, a vtol and a wheeled tank along with a ton of other new features and changes. come play if you have crysis wars, or better yet, buy crysis warhead just for this because its worth it.
It being a mod it takes a slight of effort to get working the way you want it to, so have this link to a starter guide on the MWLL forums:
http://forum.mechlivinglegends.net/index.php/topic,18022.0.html It should also help you not ragequit right away, this game has quite the learning curve to tackle to go further than newbie level.
PS. MWO is probably going to be coming out within the year but i don't think it's going to surpass MWLL in anything but convenience for some time to come. They also have fundamentally different mechanics and game design in many areas.