As the title suggests - it would be lovely if you could let us create trees with subcategories in our game collections/ folders; examples - one could choose to further split his Rogue collection into roguelike/lite or RPG into action/ turn-based or TD into classic/ survivors-like and so on.

This would be a QoL addition for the casual player base that prefers to play lots of smaller/ indie games. Once such a player hits 100+ games, the standard one-level list becomes way too long for a practical per genre split (at least in my experience).

Hope to see this simple addition someday.

Many thanks!