Thank you for the comments! Glad you liked the game.
I agree that more variety would improve the gameplay, unfortunately I don't think I'll have much time to work on this game in the near future. I did however update the game so that the speed increases while you play. This should provide an increasing difficulty level, and hopefully a more challenging game. This feature was also in the original Applet, but the increase was really slow, so nobody probably noticed it.
Also good to hear that the software renderer works fast and smooth enough on different systems.