From Mario City Games:
Wyspa Gier is another fangame created by Edenburg the Mario City game creator. This free fangame is basing on Super Mario Bros realm, you mission is to complete eight magic doors. In start of the game you will be placed in the dark room with lights and magic doors, by entering ony of the door you will be transported to level - if you will complete the stage you will gain magic key to another magic door. The idea as always is simple if you have played Super Mario Bros game you will know how to play.