The 990 is bassy, but most of its bass is mid bass, not deep bass. As far as open cans with deep bass goes, the HE400 and LCD2 hit the deepest. The X1 is very good on deep bass, but bigger on mid bass. If I had to choose on bassiness, definitely the X1 has more of what I look for in terms of emphasis and presence.
You can't expect a lot of deep bass from open cans, and they are few and far between. Don't expect it for cheap, either.
My recommendation for you for gaming of all types is the Philips X1. For more balance, yet still very good bass, the K702 65th Anniversary.
In other news:
Dealzon has a lot of sales for PC games. I just got the last DMC (Devil may Cry) for $24. It's the lowest it's been ever, and I didn't wanna wait any longer for it to go down. I knew it'll probably go down like another $10 in a few months, but I can't wait that long. Been waiting to play that game for like ever.