Yeah, I think you can break the complexity of it in 2 or 3 levels. So the player can get used to the options more gradually.
Hm, would switching between two colors really be much easier than switching between three? You only have to pick one tower color per wave, so it seems like it would be relatively the same amount of challenge, just with one fewer menu option.
But if a lot of people asked for the color red not to be in easy mode, for example, I would definitely do it. I just need more data and opinions!