Boxxle is a Game Boy adaptation of Thinking Rabbit's puzzle game Sokoban. There already exists a TAS for Sokoban DS and I wanted to do some for other releases. The puzzles used in Boxxle and Boxxle II appear in several other Thinking Rabbit releases, such as Shove It for Genesis, so the solution sets for those puzzles can easily be reused to TAS other games in the future.
I wanted to make a video showing off the minimal moves needed to complete every level; however, while the number of steps in the best known solutions are available online, the solutions themselves are not posted publicly anywhere, as many Sokoban fans want to keep them to themselves. As such, gathering the solutions for this TAS was actually several months in the making; I used computer programs (JSoko and YASC) to optimize solutions the best that I could, and traded solutions with users on Sokoban-Online and LetsLogic.
In the end there were still 4 levels I could not figure out the best-known moves solution to: 6-6 (1,383), 6-8 (757), 7-2 (548) and 10-7 (966), as the holders of these solutions were unwilling to share them with me. If I ever figure them out this is an obvious immediate improvement.
Other possible improvements
1. Sokoban levels are actually quite complex from a computing standpoint and it seems possible that even the top solutions I have now might be eventually improved upon
2. Getting the first frame input on movement is easy because you just have to hold in the direction you plan on going while your character is in the middle of moving. Nevertheless I did all of the input for this TAS by hand so it's possible I messed up somewhere. If I ever do another Sokoban TAS I'll want to write a script to convert my text solutions to controller inputs to eliminate the possibility of human error.
3. Possible lag reduction? It doesn't seem relevant here but I haven't investigated it.