It’s a short list. I used Apple’s Xcode tool and SpriteKit framework to program the game using the Swift language. I used the app Acorn to create the letter tiles.
Some auxiliary tools I used include git for version control, Bitbucket to store a backup of my code online, and the app Asset Catalog Creator to generate the app icons.
If you’re wondering why I used SpriteKit instead of Unity to make LetterMiner, I did try Unity before I settled on SpriteKit. With Unity I had a hard time getting the tiles on the game board to line up properly and determining what tile on the board was clicked. I had a much easier time getting a prototype working with SpriteKit so I stuck with it.