The purest duel
Every tournament ends heads-up, and cash players who never practice it get eaten alive there. Two changes run everything: you post a blind EVERY hand (waiting now costs double), and there is only one opponent (your hand only has to beat one fan, so its equity soars). The result is a game where aggression is the default setting: you will play most hands from the button, defend most from the big blind, and fold less than feels comfortable on every street. Wide is not wild — position, initiative and pot odds still run the show, just stretched to duel scale.