Recently I bought the AI expansion pack using pizza and was slightly surprised that the game did not request any sort of confirmation from me. It just snatched the pizza right out of my hands! Without asking me! (Though I did agree to it). So to the actual suggestion: Usually in games when you use premium currency to buy something it asks you if you're sure, right? Since pizza is premium currency, if you click something that requires pizza, a small pop-up box should appear asking the player if we're sure with two options namely, 'yes' or 'no'. Of course there will be a small checkbox in the bottom saying 'don't ask again' for those who are irritated by this. (On an unrelated subject, forum suggestion: Instead of having to type [Suggestion]/[Question] for threads to specify the type of thread, how about adding preset tags that can be used by players? Clicking these tags on the main page would show only threads with those tags. I'm not sure on how to explain this better, but if I'm allowed, I'll post a couple of links to other forums that use this feature.)
Yep I think the suggestion of confirmation as been suggested before and it is indeed a good idea. Also I like your other suggestion.
