Probably your graphics drivers are outdated.
Recent community posts
You can download the game as 3.5 and the new v4 in alpha. It is already a full version since almost a year now. The web version was downgraded because some new features are not supported in the web version.
When trying to jump onto a platform, sometimes the game will freeze and when you move you are suddenly on the ground. It was a very short gameplay and when you finished the game it was very sudden.
I find the first enemies (biting) to be very hard to kill, they have a small hitbox, then the shooters are really easy to kill. At the second level it got too hard. I will also mention that in fullscreen, some things were off-screen. Overall a great game.