Thank you for the detailed feedback.
Regarding the problem with the crystals, they spawn randomly and are all around the map which might have all spawned in the center of the map.
Regarding the player suffering from too much inertia, that can be changed by adding more friction. The intention was for the player to be able to do some Tokyo drifts. The enemies didn't have such properties as I didn't know how to code it and as it is sometimes impossible to dodge the enemies coming straight for the player, it is an incentive to collect the gems for additional health.
I intended the asteroids to be there to help the player but due to some technical restrain as the asteroids gain a lot of momentum as they collide with each other which can cause lag due to a large amount of calculation.
Thank you for taking your time to give feedback for my game thx!