Mega Man 2

Widely considered the best of the classic NES Mega Man games, Mega Man 2 sends the blue bomber against eight new Robot Masters — Metal Man, Air Man, Crash Man, Flash Man, Quick Man, Bubble Man, Wood Man and Heat Man — before the fortress stages and Dr. Wily himself.

Its innovations still define the series: a stage-select screen that lets you attempt the eight stages in any order, a weapon-copying system where each boss yields a power that trivialises another stage, and the Charge Shot from the sequel onwards never existed here — instead you get Energy Tanks that store spare health, and a difficulty select that genuinely changes enemy behaviour.

• ▸Free stage-select order across eight Robot Master stages
• ▸Weapon-copy system with boss weaknesses to exploit
• ▸Energy Tanks that store health for later stages
• ▸Password system so progress can be resumed without a save battery