In 2014 my kids developed some simple games using Applesoft BASIC and a real Apple ][, and they had a great time doing it. Here they are: Bomb Run and Maze Trap. These are bootable ES-DOS disk images (ES-DOS is compatible with DOS 3.3), so you can run them on an Apple ][ emulator.
I intend to put more here in the future.
If you're working with real Apple ][s, ADT Pro is a great tool for transferring data between Apple ][s and more modern equipment. Call A.P.P.L.E.'s APTEST (alternate source: Call A.P.P.L.E.'s APTEST) is a good diagnostic tool. There are many Apple ][ emulators; for Windows a descent emulator is AppleWin. Here is a good simple Apple II Applesoft reference. Jobs And Wozniak Talk About The Company's Beginnings has a short video from 1984 about their history before then.
"Clone Wars" (Tedium, May 4, 2017) has a historical summary of Apple ][ clones.
Here's an Apple ][ the size of your hand.
You can also view my home page.