Unfortunately I have no idea how to work out if making a game is "worth it" or not. You've got a clever enough mechanic that you could expand it to a full game, but it's also a bit niche. The people it appeals to (like me) really love it, so if you're okay making a game for them then totally worth it!
But it seems like an idea that might be a bit too confusing for many people, so would be unlikely to appeal to a broad audience. Ultimately I guess it depends on your motivations for making games as to whether you think it's worth expanding to a full game.
...in short, I don't know. But I loved this.
- Joe