Boundary fix, at small performance cost.

game/game.go

@@ -237,8 +237,10 @@ func (g *Game) UpdateParticles() {
 		if g.resolvecollisions {
 			g.resolvers[g.resolveridx](particle)
 		}
+	}
 
-		g.BoundParticle(particle)
+	for _, p := range g.particles {
+		g.BoundParticle(p)
 	}
 
 }