Few things I'd suggest:
- The game is great visually, though it feels very empty. I think adding a few more decorations, like tall grass or a small garden, would greatly improve this aspect.
- The music is good, but I think it's too dynamic for what seems to be calm and relaxing childhood memory. Maybe something calmer would fit better.
- I think adding some sort of indication of how many fireflies you've caught other than a number on the screen would make the game seem more interactable.
- The game might need more gameplay depth other than spamming E (by the way, please state controls at least somewhere) in a designated area. Like maybe physically moving the jar to catch the fireflies or a minigame about it.
Other than that, it's a unique idea that fits the jam's theme really well.