I found this information about Stasis on the GOG forum:
The game autosaves every time you go to the menu screen.
To manually save, access the menu, click Load/Save, then select one of the slots on the left,
it will highlight, then hit save. To load, do the same thing - access the menu, click the slot (it will show a screenshot) and then click load.
Inventory is shown when you put the mouse cursor to the lower left corner of the screen.