8
At first I thought it was unreasonably hard, then once I established 3 simple rules, I thought it was unreasonably easy on any level:
1. Only click enemy squares in the middle if they are even.
2. Only click enemy squares on the sides if they are odd.
3. If you can find no squares for 1 and 2, just make a new one.
This won my match 99% of the time, at least against the computer it did.
So yeah, there should be different wild cards added to actually help strategy along a bit.
I also usually don't like ripped music, but the dust brothers work well here.