Love this! Would run it.
The time-abyss gut-drop feeling of going into the future instead of the past is a great hook. The villain being a former ally corrupted over time is also really great. The themed dungeons are good, though the water dungeon not having a single boss like the others felt a little underwhelming.
It would have been good to have a bit of information gathering possible so the players can strategise on which order to tackle the areas. The rumours feel a little weak. I think there should be more of them and have more useful information about the challenges the players are going to need to overcome to succeed. Without good information all destinations feel like the same choice. Hearing additional rumours from the wandering NPCs would make running into them even better, I think.
But the main point of improvement I see is the way the dungeons are keyed. The big blocks of tiny text are just very hard to parse easily. I'm sure if you reformatted once free of the jam's restrictions you would overcome this, though.
The only other thing I would love to see is just... more! Fleshing out the wasteland a little more with some meaningful navigational choices (do we go through the rust pits or the sandstorm?) for the players would be a good addition, imo.