Compose items to build items: Anyone can mint a single letter (although it gets harder over time), but to mint words, you need to own its components. For example to mint a "cat", you need to own the letters "c", "a", and "t" in any combination. (You could combine "c" + "at", combine "c" + "a"" + "t", etc.)
Unbounded total supply: ASCII works like natural resources. Anyone can discover and mine resources and use them to produce valuable derivative goods. Likewise, anyone can mint ASCII and there is no limit to how many can be minted, but it organically becomes harder and harder to mint as the demand goes up, just like how natural resources become scarce over time with increased demand.
Organic scarcity through time: Every item has its own "cool down" period. Every time an item is minted, anyone who wants to mint the same item needs to wait for certain amount of time before being able to mint again.
High demand items increasingly harder to mint: The cool down period increases proportionally to the total supply of an item. This means an item becomes harder and harder to mint as the item becomes more popular (learn more about the algorithm here).
Processed goods harder to mint: The cool down period also grows proportionally to the number of letters in an item. This means the more letters an item has, the harder it is to mint. This makes larger items valuable, and in turn makes the smaller items even more valuable because you can only build larger items by combining smaller items from your inventory, just like how you build processed goods by combining natural resources.
Infinite game of building: ASCII is a game that never ends. And you own everything you create. There is no upper bound to how valuable your items may become because the more they are used, the more valuable they become (This is not just some philosophical hypothesis--The items literally become mathematically more valuable proportionally to usage). ASCII is unique because collecting requires using, and the value comes from usage.