On consoles, the only thing I can think of are Front Mission Evolved and the AC games. You could buy MechAssault 2 and play it on your 360 since it's backwards compatible. I can't think of any mech games on Mac. But on PC there's MechWarrior Online. It's F2P, but does a good job of not being pay 2 win. I've been playing it a lot the last week and a bit and it's pretty fun. Expect to get owned a lot early on, since the starter mechs suck ass. Once you have enough cash to buy your own though, the fun begins. MechWarrior 4 is also freeware, but it's an older title. There's also Hawken, but that's a bit more arcady than MW.