Has Real potential
i really liked it it gets addicting butt heres a few things you could do to increase its potential even more:
1. Add a bigger diversity of enemys.
2. Make enemys move faster as levels increase.
3. Increase bounties on enemys but add a cooldown time to the money powerups.
4. Make different powerups such as 2X Walk Speed, 2X Shot Speed,
Explosives, Money Multipliers, Etc
5. Add another difficulty
6. Add boss fights every once in a while
7. Create a level and kill indicator
8. Make upgrades for base like turrets, towers, size, and design.
I'll add more later if you decide to add these in later updates.
Hope you appreciate this
Orion928