On steam, many games drop "cards"; the idea behind this thing (other than, of course, promote the inner market of digital goods they are also selling on TF2/CS:GO) is intended to trick people in "daily return". Sort of neuroscience trick that pushes customer back in the store even if they have absolutely no reason to do so. This "trick" is known to be used in social games like farmville (players were ask to "return tomorrow" to obtain extra goods) and the recent infamous harry potter mobile game (stuffed with lot of this sh*t).

Now, there's no need to be greedy/evil like those companies who use neuroscience: itch.io feels more "flat" in relation between customer/developers, as it seems everyone is on the same floor here. So, my idea is a lot more paceful.

Fork minetest, and integrate it in the store: default server is, of course, itch.io. Customer can have access to itch.io online server only if spent at least 5$ in itch store, otherwise itch.io app will simply set up a reduced server on customer machine: a small world of few chunks of data, so it's easy to synchronize on cloud his/her small across all the machines he/she install the itch.io app.

When customer is online with his/her own small itch.io world, can invite its own friend (with itch.io app as well) into their "home". The basic itch.io account/app sync world with only basic nodes... but as customer buy more games/stuff, they obtain more digital goods (in minetest can be as simple as an animated sprite) exclusively to what they got in their library (similarly to steam's "drop cards"). Since cloud synchronization is centralized by itch.io server, it should be relatively safe for the app to sync only digital goods (special minetest nodes) in which customer actually own.

Complexity of available nodes (ie: simple sprite or 3d mesh) will depend on the volumes of sales each game have directly on itch.io; this to avoid clutter the server database with useless and complex junk.

ie: games with sales up to 1k may "drop" simple sprite nodes or midi/mod soundtrack

10k volume sales may drop simple lowpoly 3d models or .ogg music

100k volume sales may drop a AI pet/mob officially taken from videogame cast of characters/npc.

Probably technically not feasible, companies with way bigger resource would had already prototyped, but still a nice idea to think :D

nope this system steam has is been used to abuse players and customers. It is never going to work, the only reason steam has it is because they are lazy to remove it.