Manic Miner is a remake of the 1983 platform video game initially written for the ZX Spectrum. You can download all 71 of the Crozza Remakes here.
Like many of his remakes, the game is accurate but has different graphics and colors. You will see several flashing objects, including keys, which must be collected before Willy's oxygen supply runs out. Once you collect all the objects, you must return to a now flashing door, typically where you stared. Then you proceed to the next level.
F4 will switch from full screen to windowed mode. Left and right arrow keys move you, and the up arrow key is for jumping. Like all Crozza Games, the game is portable, so no installation is needed.