I really liked it! I love how the ads are upgrades and not just an annoyance. Could have had a background to make it look less like a demo build though. If the jam was longer I could totally see more upgrades and zombies.
We are really unhappy that we had to submit with a placeholder background too. Unfortunately we had issues creating one before deadline :/
There are in fact a few leftover assets which did not make it into the game due to time pressure.
Thank you for your review :)
