My main suggestion has to do with my only real problem with the game: the controls used to interact with objects in the game.
Currently, they feel kind of counter-intuitive. For example, the number of times I've wanted to use the hot-bar to ready my crow bar only to realize that I can't because my pointer is over something else in the game world is too high to count. Here's what I'm thinking would make for a simpler and smoother experience:
- Press E once to collect items in the world. They go straight into the player's inventory.
- Press and hold E while the crosshair is over an item to pick it up and hold it, for the purpose of moving things around the physical world. This could be restricted to only working when the player's hands are empty.
- In the player's inventory screen, they can set specific items to specific spots on the hot bar. There could also still be a Use button for using whatever consumable item (like food, or batteries), a Drop button to place the item at your feet, a Place button to put the item where your crosshair is, and an Examine button to get more information about something in your inventory. Maybe equipped items could just have a big letter E next to them, and be pushed to the top of the player's inventory list, rather than disappearing to a separate inventory screen.
- While using an item in your hands via the Inventory / Hotbar system - or while holding an item physically in the game world - press T to throw the item, or press G to place the item down more gently. Press R to empty the player's hands but keep the item in their inventory.
As an unrelated-to-inventory-management suggestion that I still think would be interesting, maybe make the codes to the front entrance and security room be randomized each time you start a new game.