In general, you want to maintain a CTR above 1% or you'll find Google gives your spots to someone who actually generates revenue. This of course depends on the competition in your particular niche.
You don't make bingo card software, so it is likely irrelevant, but I get about 3.83% CTR on ads on the search network. (That excludes my holiday campaigns, which -- when Google actually approves them on time -- are so effective they should be illegal. 10%+) Things that have helped me: Conversion Optimizer, writing copy until it "clicks" with the users, and a few years of work.
By way of comparison, I only get about 2% or so on the content network.
After you've got a better CTR (and, not incidentally, are spending more money) you'll see Google offer you more impressions, and then you should start working on your CPA, because if that is doing poorly all the clicks in the world won't help you.
AdWords gets fractally complex if you're new to it, since you have to balance your business requirements against Google's interests and policies (which are not disclosed in a thorough fashion, change frequently, and are capricious and arbitrary). Best of luck to you.