(The story for) Very Cool Gun (VCG): A Rougelike Shooter with Only One Gun

Game Mechanics

Yuko must work her way down through Sheol's different "tiers," using the VCG to fight off wildlife, the Out's forces (who know they are on the planet but don't know to find Home), demons/monsters from the depths of Sheol, and more. Many different kinds of loot and items can be found all around the "floors," like currency for both the current run and overarching progression (being Elytrum), single-use items/buffs, and most importantly, various randomized augmentations to the VCG which change it and Yuko in radically different ways, such as giving the VCG a new "type" of weapon to turn into, improving its stats like damage, fire rate, ammo capacity, etc., a new movement ability/boost to already existing movement abilities, augmenting Yuko's health, movement speed, health regen, etc. Because of the VCG's extreme form-changing abilities, almost everything Yuko does aside from basic movement is done by the VCG, such as shooting (obviously), melee combat, extra movement abilities like double jumping, airdashing, wall-climbing, etc., storing keys/other items for later use, etc. Dying causes the player to lose all in-run progress, pretty much anything collected during a run is discarded upon death and each run has a completely randomized layout, essentially putting Yuko back at square one at the beginning of every run, though certain items and a recurring "progression" currency in the form of Elytrum stick with Yuko between runs. New items/augmentations can be unlocked through a variety of means, such as finding them in the world (sometimes important mods/upgrades spawn in pre-programmed generated structures and can only be obtained after unlocking other upgrades further down in Sheol, similar to a Metroidvania), buying them in at the shop in Home using Elytrum, or by completing missions and challenges. This will introduce them into the item pool, allowing them to be found in future runs. Elytrum can also be used to purchase permanent minor stat increases for Yuko, so as she repeatedly dies and starts over she progressively grows stronger and the game becomes easier, allowing her to explore deeper and deeper into the world, collecting even more things and growing even stronger, until she eventually wins.