This is a ROM hack of Mega Man 3, specifically Rockman 3 - Dr. Wily no Saigo! (Japan), created by Rock5easily in 2009. The "Endless" designation implies significant alterations to the game's structure, potentially extending the campaign length with additional levels, enemies, or challenges. The original Mega Man 3 is a platformer emphasizing precision movement and strategic weapon usage.  Without access to the hack itself, the exact gameplay modifications remain unclear, but it likely adds replay value to the original game.  Hacked versions like this often have an enthusiast community creating and sharing the modifications.

Rockman 3 - Dr. Wily no Saigo! (Japan) [Hack by Rock5easily v20090301] (~Rockman 3 Endless)

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