Not sure which part of the forum is best for feedback. Since this is about The Ruins I'm putting it here.
THANK YOU for giving us a campaign that isn't all challenge levels! I know that this is supposed to be able to be done using just the Dungeon defenses, but I'm having more fun because I love my lightning tower and perforator, not to mention mana crab and the option of using repair, etc. Later when the shiny has worn off the levels I'll see if I can do without (some of) those.
A suggestion for a future release: if I hadn't been reading the forums it might have taken quite a while before I discovered that I could click on a door to make it open or close. Since it's not exactly a defense (you can't place them yourself) it doesn't show in the Tinypedia. Could we please either have it added to the Tinypedia (and possibly in the future we might be able to unlock placing them), or have Carl pop up on the first level of this campaign to explain about the doors?