Add game 4: star map

[K-Meech]

For #17 (see the extra info from an email chain with David on this issue)

Adds:

• a constellation of 10 stars, that light up in a random sequence, then ask the player to repeat
• repeating in the same or opposite order is randomly chosen per session (currently shown as text in top right, but eventually we probably want to integrate this with the intro instructions / make it more visible)
• stars are selected by locking on with gaze for 1 second
• Every correct sequence increases the length of the next. Getting two sequences incorrect in a row decreases the sequence length
• Game ends at 5 correct sequences

Any comments / suggestions very welcome! I think the only part I haven't implemented here is the spinning of stars on selection (as suggested by David on the issue) - happy to add this in a future PR, probably once the star graphics are confirmed. Using colour / size change for now seemed the easiest option for getting the basic game structure up and running.

[thompson318]

This works for me and meets the brief. I found a couple of hard coded delays that should be made configurable before merging. I found it quite hard to play so I think it will need further development after team meeting / play testing. Some ideas:

• It would be helpful to differentiate between when you're being shown the sequence and when you're expected to follow the sequence. For now we could just change the background colour to make it obvious, but may require thinking about the artwork.
• I found 1 second too long to maintain gaze on a star (got bored plus my eye tracker is quite jittery), but if you make it too short or have too big a collider you risk accidentally triggering other stars. You could set it up so that gaze selection time is different for correct and incorrect stars.
• It took me a while to learn the game mechanics. To make it a bit easier when you're learning the game mechanics the next star in the sequence could wave at you.

[K-Meech]

@thompson318 - I've removed the hard-coded delays you mentioned above, and added your other comments to the issue (to address in future PRs): #17 Would you be happy for me to go ahead and merge this? My plan was to work on adding smoothing / averaging of the gaze position for this game + star seek next.

@mmcleod89 - if you have any suggestions / comments, feel free to still add them to this PR or the issue. Then I can address them in further PRs 😄

[thompson318]

@K-Meech, yes please go ahead and merge when you're ready. Any improvements can be made in later PRs.