This is why, even though I make a living doing software development, I'd never, ever risk it doing games. The cost/risk is too great.
Though 8k copies in the first month really isn't too bad for the average indie game in today's climate. I've seen really good games do *a lot* less. For example, I'm a big fan of 6-DOF shooters, and I watched NeonXSZ push under 2k copies.
As for the specific game... I'd never even heard about it before now. I do like mech games, but I'm more of a "first person, in the cockpit" kind of player, so I don't know if I'd pick it up.
I know devs hate to read this, but: Maybe I'll try it when it's in a bundle. I've got way too much stuff on my plate already. I have surprisingly little "real life" stuff, but I still haven't even found the time for games like Wolfenstein: The New Order, or even finish Doom, yet.