Universal Paperclips
en.wikipedia.org
en.wikipedia.org
Super minimalistic UI.
The habits and reflexes it embeds while you play is a kind of management and awareness of "spending" your limited attention and a furious trying to figure out and model how things work and fit together.
It really gave quite a pleasant buzz.
It has all these little sub-games that keep getting added without explanation, you try to make sense as it unfolds, trying to figure out how each bit works and how it interacts with what you have so far.
There are multiple goals and you keep having to choose based on super incomplete understanding what to aim at and focus on next.
It was also quite humourous in a dark, sardonic way: you establish world peace at some stage (as a subgoal of increasing global paperclip production), only to eradicate the entire humam race a while later (to increase solar-system wide paperclip production).
Loved it!