This is a great game and it is really addictive. I personally found the game easy to complete, but it was filled with moments that I thought i was going to fail. There are a few bugs, such as the game not loading the next level after exiting the upgrade menu (simply restart the level from the pause menu to fix this), or being stuck with the main menu background after exiting the upgrade shop from the level select menu. It's really fun, despite the bugs I found.