Fantastic execution of a neat premise. Visual style is great, with runic-looking numbers playing into both the gameplay as well as the aesthetic, but I'd especially like to highlight the fantastic sound effects - Clicking and dragging numbers feels super clean.
The only points of feedback I'd give is that it is a bit too easy to trial-and-error (which isn't bad for a jam game) meaning I didn't feel incentivised enough to sit down and study the mechanics and figure out how it worked. Additionally, the fact you were forging a sword didn't really play into the gameplay at all, as it could well have been swapped for the teeth of a key instead (don't think I didn't catch that!).
But no, it's a great little puzzle based on trying to figure out what time it will be in X hours/minutes.
Viewing post in Forge of Time jam comments
The sword is built from several elements. The mask controls the border shape. The shape itself is achieved by applying a height map to a flat color with a simple light source. The height map is always the same — it doesn’t depend on the border shape. When the sword is motionless, the shape is cached and only the mask changes. When it moves, the height map is applied every frame.