Suffice to say, Udo now has music on the title screen, in-game music that can be specified in the level file and a few basic sound effects. Since these may not be to everybody's tastes, I've also added a Sound On/Off option to the in-game menu.
I've also just added in a lives system since it seemed quite quick and easy and involved shuffling my sprite banks around so better now than later.
I think the idea will be that when you die, you restart the level that you are on but preserve your score. The levels will be grouped and when you complete a group, your progress will be saved so that after you lose all your lives or restart the game, you start again at the same group of levels you had last time.
I'm even tempted to come up with a between-levels select map like Mario had, where you move from point to point and unlock a point when you complete the group of levels it leads to.
This will avoid the need for a complicated mid-level saving system and will be okay as long as the levels are quite short, although if I can think of a good way to have mid-level checkpoints, it would be far better really.
Have to ponder that one.