I'm making a list of future changes:
- something to help with the speed initially, i still want it to build up, so maybe a difficulty level.
- more powerups / upgrades, I have some ideas for new weapons and enemy types, including new textures.
- continues / scores, the scores are a bit "tacked on" at the moment, they don't serve any purpose beyond personal achievement. I'm thinking to either link them to powerups, so every 100 points = new powerup appears and/or link them to "continues" in the same way. Currently the game allows you to continue at the start of each level any number of times, and because of this, I reset the scores (the penalty for dying).
Let me know if you have any suggestions!