This engine is incredible! 200+ bouncing balls that all collide and still 300+ fps on a low end computer. Just a couple thing, i notice the players movement doesnt get reset when they jump below a ceiling and just float for a few frames. Second, i couldnt find any documents on this but is there or are you planning to add normals to collisions to change the slide/bounce direction? which also brings me to, are you gonna add sliding down to the player on steeper terrain?
