A very, very good game.
RS23 puts you in the shoes of Clare and what happens during an unfortunate fuel stop.
Graphics are both functional and very well drawn: the backgrounds evocative without distracting from the action, enemy sprites — some small, some big — each one exquisite and smooth.
Gameplay is metroidvaniaesque with a reminiscence of nethack: you will jump and avoid monster, avoid scary and dangerous spikes too, and save your progress at rest stops (no save: lost progress!). There are some power ups that will help you, collect them all (including each health powerup), as they will unlock different parts of the underground.
I will warn you that some parts are not easy and will take time and a mental map of where danger is (with the usual rule: die → rest stop). Map space which is btw very cleverly used, the world is so big yet so compact and cosy at the same time.
Minor bug: wall jumping between screen transitions sometimes does not work (takes multiple tries).
This is not “a very good jam game”, a “very good game” full stop! Congrats to the team.