Here is my Oculus playspace with the Guardian Boundary Editor:
The problem with the playspace is that you use the blue walls as a base and not the green playspace. The blue walls are exactly on the real walls, which makes it easy to run against the walls which is very uncomfortable. For this the Guardiansystem is not thought or suitable. It is also the first game where I turn off the Guardian system, because you are always so close to the walls and that bothers a lot when it is displayed. Incidentally, i have had games that temporarily disable or fade in the Guardiansystem permanently.
I can think of several options for calibrating:
1. A slider which reduces the entire playspace by xx percent (easy to implement)
2. Run through the playspace with a controller as in the oculus setup or press the trigger once in each corner.
3. You blend in the playspace on the ground and you change the size with the help of some points as in an image editing program when inserting a graphic.
Do not make the game endless, but more difficult with each level. With permadeath and a high score at the end which is stored in a highscorelist. That should give enough motivation to continue playing.
How about incidentally with selectable settings? For example, the current sci-fi setting with robots and laser weapons and a second setting with swords or knives in a dungeon. A space station would also be possible, since you only have to change the background with stars. Just an idea for the future...
If there is interest, I could translate the English texts into German, if at some point there is a bit more text or a tutorial (necessary, I still have not understood many things).