There are in-game instructions that go over what you need to do. All enemies have a red outline. The little grey you need to keep distance from, and also protect from the other enemies, you can get close to give it a blue shield that protects it from damage and heals it faster. The robots have more HP than all other enemy types, but move slower.
Unless you mean that the game is actively glitching? I am not sure, seemed fine playing from my browser and locally.
The game is also pretty difficult. Thanks for leaving a comment though.