Super Sanctum TD is typical towers defense game, nothing more, nothing less.
Yes, this game looks on screenshots like 20 years old game which may be repulsive. I don't even know why I started to play this game, but for sure I didn't have any expectations. And I realised that I have 13 hours playtime. That was good time for sure. This game is well designed, difficulty level grows with every level, so it's not so hard to start but it's getting difficult after some time. But you will want to pass only one level, and next after that, and maybe next... And so on.
Generally very well designed, polished and properly balanced piece of a game. It's really hard to find something as good in such a price. Good job.
If you're a fan of tower defence games, this is good one. Try it, you won't regret.
If you have only few bucks and want to play for long hours, this is it!