The Tower is a defence game. You stack up defensive blocks and use spells to protect your main heart block.
I suggest normal difficulty first, if you find that too hard after a few goes trying out different strategies maybe drop back to easy.
Rich mode is just for mucking around at the start to build a tower however you want. Only play this after you’ve played the game properly.

General Tips -
- Flying won’t attack your heart if it’s not in line with them, but will pose a threat if you build high. So be careful.
- Cannons work better the higher they are. There range & accuracy is based on there height as you will see.
- Try to use a bit of everything, don’t stick to just defensive, or just offensive.
You could call this game a “Tower Defence” but it really isn’t at the same time :P a little twist on the genre in a way you’ll see :)