OMG, I just discovered by accident: you can replace your current piece by tapping the 'up' arrow!

But something is bugged, I ended my current round and began a new one, but my "gem" count remains at 0 now?

OK, I quit the program and relaunched, and now it's at 10 again, phew..... I thought I was going to have to spend real-world money to buy more gems or something

This would be a good bug to fix, so I don't have to relaunch the entire game between each round!

It gets stranger: During gameplay, I created a large block, and this rewarded me with a bonus gem (bringing my total to 11, because I hadn't used any yet). Then, later in this round, I used all my gems, and then got game over. When I started my next round, I had 0 gems, as discussed above. HOWEVER, when I relaunched the game to fix this bug, and started a new round, I now had 11 instead of 10??

ok, after achieving a few more bonus gems, my total went up to 13 for a while -- but now, when I relaunch and start a new game, I always start with 6?? so this clearly isn't just "oh your gem total increases with playtime"; something is bugged

I've identified the bug:
- When you use a gem, the new lower amount is not written to the save file.
- When you GAIN a gem, your CURRENT total is written to the save file.

So:
- if I begin a game with 40 gems
- and I use gems until I only have 30 remaining
- and then I lose and relaunch
- I begin the next game with 40 gems.

But:
- if I begin a game with 40 gems
- and I use gems until I only have 30 remaining
- and then I gain one gem
- and then I use gems until I only have 20 remaining
- and then I lose and relaunch
- I begin the next game with 31 gems.

Hahaha, thank you for exploring.
My initial design was like this: the game has two modes, one is the normal mode, and the other is the simple mode (now renamed as Practice).
In the simple mode, there are always 10 gems at the beginning, and no matter how many gems you get during the game, they will not be saved. In normal mode, you will get a gem when you combine 1024, and it can be saved for later use.

So in fact, the Practice mode is just for beginners to practice because it doesn't have much difficulty and there won't be any random numbers.

OK, but is it intentional that if you gain a gem after using several gems, your total number of gems goes down ever after relaunching the game? (And if so, why does the total not go down if you use them without gaining any?)

Could it be a bug? I check...