Click to mine virtual Bitcoin on an old calculator, then buy a slightly less bad computer, then a Raspberry Pi, a smartphone, a cheap server and eventually a mining farm. The joke is in the shopping list, which climbs from a grandpa's old PC through NASA machines and a quantum rig to a mining farm on the moon and a black hole powered miner.
Everything is counted in real Bitcoin denominations, so the early game is spent watching eight decimal places crawl and the late game is spent watching them stop mattering. Development stopped a while ago and the author has said so. What is there works, saves, and runs about an hour before the list is exhausted.