Hey, just want to say that as someone not usually into the ASCII look I like what you've done with visuals of Dungeon Mercenary. Understandable if you move on, though I think you could go further with Unicode characters (walls ◢■▩🮒🮁🙫🮕🮙, enemies ☠♞🕷, character 🯅, etc ☁⛊🗲⎚⁍⚿🗝❄⸾🁱) or even color unicode 🍓🐀🐉🌟🏺🚪🪨💗. Maybe even some simple combinations (2-3 layers, auras etc)?
Simple polygonal art could also be mixed with this and go a long way. This is possible with tilemaps (using scenes) in Godot 4.X but the main issue would be lack of AA in the web(+mobile?) export or tilemap clunkiness.
Back to your games, I think the biggest issue with UI is mouse-hover descriptions being too overzealous... making enemy descriptions on right-click so you could add pathfinding (when not interrupted) would help. I would probably also make the forge able to merge items per-type (equivalent to melting non-equipped+applying in one step) and also make spells not take (normal) inventory space (or allow them to be merged/recycled in a similar way).
Personally I would like more options/opportunities and especially more slack when it comes to inventory management, as combat will still be the biggest factor.