So the latest build has the first rev of the Store in Combo Storm. I've been itching to add this but also fearful of how much would be involved. Fortunately a friend of mine (Ryan Ellis) gave me some solid advice on how to approach it for the first run and I was able to squeeze out on a snow day from work.
In Combo Storm, when you perform combos the weapons involved receive points and will eventually upgrade. Originally there were 3 upgrades per weapon (except gas can). Each time you start the a level you lose all your upgrades and need to start over. The store adds a new dimension to that.
You earn cash when playing (the little orbs that fall of guys who have had combos performed on them). That cash can be used in the store to upgrade 2 things: Max Upgrade Level and Base Upgrade Level. By increasing the max, you can access higher upgrades via combos. By increasing the Base, you can make a weapon permanently upgraded. Base upgrades are much more expensive so if you are a skilled player you can work on increasing the max and earn them during levels.
At this point I am going to take some time and start really balancing the game. Hopefully in a week or so from now I'll have a new build that is a lot more fun and easier to get into.