Yes you can.
I dont think that is possible
no its a cheat
I have
Press d on the menu screen to get another player
I scanned mine with Malewarebytes Premium and it didn't detect any, so I would think not
In Mari0, saving your game progress is done automatically at the end of each level. You can also manually save your progress by pressing the "Escape" key to open the pause menu and selecting the save option. Additionally, the game allows you to load saved games from the same menu. Remember that if you quit the game, your progress will be saved up to the last completed level.
Hit the escape buttonDid you know that you can make a custom level, and than test world 8-4 to get axcess to the cheats menu in options