Scratch

So I'm working on a project, the basic idea goes like this:
You control a robot, collecting "bytes" in a maze. But instead of standard controls, you have to give the robot commands, like "3MRML2MG", which would mean "Move 3 spaces, turn right, move 1 space, turn left, move 2 spaces, and grab what's there". The catch is that commands also use up bytes. For example 3MRML2MG is 10 symbols long, so that command costs 10 bytes. You start with a certain amount of bytes, and you have to be careful to balance using them up with collecting more so you don't run out.

So far so good. I have this working already. But here's where I'm kind of stuck. What should the goal be?

Here are the options I've come up with:
1. Save up a certain number of bytes - spent bytes count against you.
2. Collect a certain number - spent bytes don't count against you.
3. Reach the exit.
4. Reach the exit while also fulfilling #1.
5. Reach the exit after fulfilling #2.
6. The goal varies in different levels.

What do you think? If you have a totally different goal idea that's fine too.