I highly recommend the documentary
Tetris: From Russia with Love. Even if you're not into gaming, it is a wonderful slice of 1980s technology with period footage and interviews with pivotal characters. I believe that cbmeeks, in particular, will appreciate it. If you're in a similar mood, you may also appreciate
Moleman's demoscene documentary. This may also provide inspiration for a rolling demo.
Despite that, I strongly recommend against implementing Tetris because it is highly addictive and productivity will drop to zero. I mentioned Tetris to Sheep20. After "What's Tetris" and watching the documentary, productivity returned approximately two months later. At one point, Sheep20 was playing a JavaScript version of Tetris over Citrix. That's hugely addicted.
Given the overlap of functionality, it should be possible to fit a
Tetris clone and
maze game into 8KB. Or perhaps a maze game and a
Boulderdash clone. Or perhaps Boulderdash and a
Candy Crush clone. It is also possible to fit
Eliza into 8KB. Some people find Eliza to be an amusingly poor attempt at Artificial Intelligence. Others find it more helpful than Cognitive Behavioral Therapy.
An ex-classmate's cousin wrote a VIC20
lake fishing simulator. When I first saw it, I thought that it was the most dull, inane game that I'd ever seen. However, I'm now beginning to appreciate the idea. Starting with $100, choose your rod, reel, tackle and bait. Then choose one of the 10 lakes which were all terrible puns. (There's further scope for puns with RAM-bow trout, carptridge and I'll skip the obvious joke but it was written in BASIC.) Choose competitive fishing or quiet contemplation. There was a particular technique to cast a reel using keyboard or joystick and the display had an underwater camera view of the nearby fish. Each lake has a different variety of fish with different temperament and different attraction to bait. After selling your catches - and possibly collecting prize money - you can buy a better rod, reel and bait before trying another lake.
If you want something more nurturing, you could write an aquarium simulator or other virtual pet system.
The best suggestion for a game is inspired by the
Crazy Ideas section of
Reddit.
Clippy Land is like
Mario Bros. which was originally 6502 only. Mario the Plumber and friends are replaced with Clippy the Paper Clip and the
lesser known Microsoft Office Assistants. (Can you believe there were 11 of them?) Unlike
Paper Mario, Clippy gets bonus items from origami cube loot boxes and dodges origami monsters before rescuing Power Pup. Or
Microsoft Bob or something. The sequel,
Super Clippy Land, only runs on 65816. Also look out for
Klippy Kart,
Clippy World and
the film featuring the
resurrected voice of Bob Hoskins.
Nintendo has Mario. Sega has Sonic. Amiga has Zool. Even the Sinclair Spectrum has Horace. We have the abandonware which Microsoft would rather forget.