For anyone who's played, or is interested in the project, I've made some updates based on the feedback I've gotten.
Here's a bullet list:
-Ammo is represented via a meter above the weapon instead of numbers.
-All weapons now share the same ammo, but deplete the meter differently.
-Ammo is refilled at the start of each level.
-Ammo can be upgraded between worlds in the Upgrade menu.
-Enemies and levels have been adjusted slightly.
-Health points in the upgrade shop have been reduced in price.
-Ammo and Life Points show up slightly more regularly during gameplay now.
Here's the link to the PC demo:
Remember there are no keyboard controls, as this is intended as an iOS game.
Here are some images showing off the new ammo meter:
Thanks for looking!