I've posted this in the old wiki and somehow it was deleted, so i'm reposting this here to show to you It's called MetroidVania Mode In this mode, the world is open like in MetroidVanias. Simply put, You can go back and forth the levels freely. There are many implications for making SMB MetroidVania-Like: 1 - Persistence of Enemies: - MegaMan Like: If they're dead, make them respawn when the screen enters their spawn point. Things can get preety hectic, though, with Hammer Bros. and such. Respawn every time you enter a new level: This feels the most suitable, IMO. - Never Respawn: This isn't much of a choice. The levels will get preety empty after you kill them all. But it can add challenge if there's a percentage score at the end for completion. Bowser defeats are persistent. If you kill bowser on 1-4, he won't be there when you go back. 2 - Persistence of Blocks: I think Mushroom blocks being reset after you exit the level should be the standard. All other blocks (Stars, 1UPs, Coins) must be persistent. 3 - Persistence of Coins: I think it would never respawn, or would respawn every level change, but it will break percentage score on coin collection. 4 - Character change: As the world is continuous, the char change should be changed to fit this. - Change when die: This only changes characters when you die with your current. - Change when change levels: This will make every level change show the char select screen, enabling you to change your char. - change at will: ou can change chars on the fly on the pause screen. 5 - Level "Unlocking": As you can take any route (1-1, 1-2, 4-1, 4-2, 8-1...) and you can travel back levels, some type of "Locking" levels that hadn't been completed. Like, if you travel forth to level 4-1 using a warp zone, you can travel back to 3-4, even if you haven't completed it? There are two options: - Lock castle levels: This will lock castle levels. If you haven't defeated bowser, you can't go back to this world. - All levels unlocked: This will unlack all levels from the start. It means ou can go back to 3-4 if you warped to 4-1. It will emphasize exploration and creation of alternate backward routes. However, i don't know how castle levels will be handled. Bowser will be the first enemy you will face if you haven't completed the level. - Can't go back bridge-broken castles: If you use the axe to defeat bowser, all the levels before that one will be locked. This isn't very good because if you are non-fire mario, you are forced to suicide to make the levels avilable afterwards 6 - Level Traveling A way you could travel thru levels are with pipes on the end/start of the levels with >> or << indicating the direction of travel. When you finish the game, a screen showing the percentage of Coins/Stars/1UPs collected, Levels completed/ Subrooms Visited (Bonus Rooms, Warp Zones, Coin Heavens.) and enemies killed will be presented, and finnally with the total percentage of the game you completed, just like MetroidVanias. I think it would be cool because exploration is limited on SMB because of the linearity of the game, but the game has lots of routes to take and plenty of secrets to discover. So you can take your time and explore the levels at their fullest. If you find errors, or would like to make a suggestion, fell free to post.