Nice idea, but:
- there should be a reason for jumping, make platforms or something like that. Increase level size when you think it is necessary.
- all larger drill robots have all similar size, try to create much larger boss robots.
- When you die, you should go back to the shop
- Allied units would be nice.
- Save game feature
- More different kind of levels and more levels in general. Try to create a city with multiple defensive locations and you should be able to attack the robots in the sewers as well (for more rewards).
- less focus on collecting stuff, more focus on shooting stuff
The game is cool, but it needs extra work. The physics are not entirely well done: the ball feels like a balloon. You should also try to implement ramps, multi-ball, and extra lanes.
There should be a multiplayer skirmish mode where players have their own cells + the ability to construct all kinds of viruses and throw them towards the opponent cells.
I want to revise my comment a little bit. It's an okay game, but there should be some kind of protection against constant losing (like losing 5 times in a row), because people might hate your game due to losing constantly.
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