I think this is a fun and very challenging game.

1. How about allowing a player to see or highlight what runes they have already successfully used for each map.

2. Although I read someone else post this I agree about a mini map preview when selecting a tower this would help player be able to plan and adjust trap levels.

3. When entering a new stage that will unlock a trap it would be nice to be able to level the new trap especially in the harder levels when a level one trap really doesn't stand up to leveled traps. Would be good to see its full potential.