If anyone is hesitant about playing TLL, it is halfway through the month and I’ve already completed the game.
Here is a spoilered list of all 9 ways that Tabitha and I found to softlock the game. This list is also credit to @David_Welbourn 's notes about the game in order to determine which items are strictly necessary or not in certain locations. I would personally rate 1, 5, 8, and 9 as Tough, 2, 3 and 4 as Nasty, and 6 and 7 as Cruel.
1. You have left the Barfee research lab without transmogrifying the two items you need (prune seeds and liquid nitrogen,) and without pressing the button on the matter mover so you can use your autodialer to warp back to it. However, you can skip the second step if you got the two correct items the first time around.
2. If you use the bike in the Terminal Velocity bar to warp to the future, and you don’t have the hammer and liquid nitrogen needed to obtain the HandyPad from the locked chest before you warp back to the present, you won’t get a second chance, as the bike’s owner will padlock it.
3. If you transmogrify an essential item before you have used it for its necessary purpose, your game is forfeit. A list of items that are essential and can be transmogrified before being used includes the bedzyl, your thesis disk, the revolt-a-kola, the hammer, the synthegg, the real egg, the fried synthegg, the fried real egg, the eggplant seeds, the frying pan, your Terminal Velocity elite passcard, the HandyPad, the ary ung, the jade figurine, the Wundur Gro, the thermos of Growth Formula, the akmid, the string, the firecracker, Squirt, the metal coat hanger, the olive drab uniform, the detachable keyboard, and the mirror. I’m not sure if transmogrifying your autodialer forfeits your game, but to continue playing without it would be an arduous task indeed.
4. Similar to the above, if you convert any essential item besides the fried real egg and the jade figurine (which you are supposed to) using the Matter-to-Digital Converter and place it in the Unnkulian Unventure III game world on your thesis disk before you have exhausted its use, your game is forfeit, because then you won’t be able to use it in the real world.
5. Get Squirt to emit sparks and light the firecracker by yelling while it holds the firecracker, in any place except by the fuse in the Akmi HQ ducts, which will exhaust the firecracker before you are supposed to use it to light the fuse. This action gives you an uncharacteristically-friendly marker of failure by deducting a point from your score.
6. If you enter the escape pod to go to Irata before you have the required items (the bedzyl, the fried synthegg, and the ary ung) to finish that part of the game and reach the matter mover to get back to the rest of the game, you’re stuck on Irata.
7. If you QUIT from the Unnkulian Unventure III game-within-a-game after having already used the real fried egg and/or the jade figurine within the game, you’ll enter back into the game and it will restart, but without the necessary two items that you need to complete it. I’m not sure if they are intended to not respawn, but it will ruin your game either way.
8. Eat the fried synth egg or fried real egg yourself, or feed them to the dog on Foon. They are required to be fed to people other than you and the dog, not to mention that you don’t have a hunger or thirst timer anyways, with the only necessary item to consume being the revolt-a-kola.
9. Drink the revolt-a-kola and let its temporary effect wear off before you’ve used your temporarily-heightened reflexes for the necessary purpose of catching the bedzyl.