The amazing thing about Parameters is that it works. By "works," I don't mean that it runs, but that it's surprisingly engaging, given its minimalist approach.
It's a sort of RPG, with level-ups, attack, defense, and health stats, and a set of monsters to slay and missions to accomplish. But "missions" are small rectangles that gradually fill in as you click on them, spawning XP and money with each click; and "monsters" are other small rectangles, with each click being a round of combat, doing damage to the monster, you suffering damage in return. Until you have the stats to slay a monster, you'll eventually run out of health, and the monster will regen quicker than you can do damage to it.