Thanks for responding. Everything you said is fair, but I think it slightly misses what I was trying to say. To rephrase, I wanted to make these observations:
1. The alien level is hard! As many have said.
2. I managed to find out what exactly makes it hard: the opponent can force a win.
3. Generally, two player games become not very interesting if it is discovered that an opponent can force a win. Even Tic-Tac-Toe allows a draw at worst. Same with checkers; for chess, we don't know yet, but it's probably the same.
4. I also tried solving the second-hardest level for me, North Korea. There black cannot force a win, perfect play leads to a draw, and indeed it wasn't as difficult :)
So, this is something you may be able to use: if in one level the opponent can force a win, then that level is probably too hard, and you may want to revisit it. Happy to share my solver program if you'd like.