Can Diablo II be solved with similar RNG logic or are there item drops and level-up constraints that make the route planning exponentially more complex to optimize?
Afaik D2 doesn't lock down it's levels in the same way as D1. The two engines are only related in the sens that some of the same developers worked on it and learned from there mistakes with the first one (which I guess makes them less related actually).
Who ever will attempt doing so would probably be best off simply looking at current RTA of D2 and probably won't find much of use in this TAS other then general Windows and mouse input.
I commented on the Youtube video about this also, but it is interesting that Groobo's run was discredited, but still provided a route and strategy for this TAS.
Groobo isn't a bad runner I think. From a charitable view he was basically trying to make a TAS without TAS tools and went a bit overboard with a few assumptions about how the game worked.
I did have some suggestions. With computer games, the "insta-mouse-move-and-click" is a bit of a pet peeve, as we can't see what is happening.
That's fair, but moving the mouse in libTAS is a huge pain. The only viable method is to input relative moves as numbers to adjust the current position, rather than performing actual mouse movements. These moves are limited to a maximum of 256 pixels per frame, and any movement beyond the screen edge gets truncated.
Additionally, opening panels or interacting with items in Diablo causes the mouse to shift as the game tries to keep it in the same logical position. There's also no reliable feedback on the current mouse position.
This forces you to minimize mouse movements and rely on keyboard shortcuts whenever possible. Additionally, making changes to earlier parts of the movie is rarely feasible since adjustments easily cascade.