Gateway Jump is based on the excellent Mari0 by Maurice Guégan of Stabyourself.net. It combines elements of the Super Mario Brothers from Nintendo and Portal from Valve. Unfortunately the elements copied from those original games made distribution of the game legally questionable. Gateway Jump removes all copyrighted material with new works.
Gateway Jump is based on the excellent Mari0 by Maurice Guégan of Stabyourself.net. They programs nearly all the code in Gateway Jump. Dennis Payne has added a hand full of features. A few other contributors can be found in the git history.
The portal graphics were made by Stabyourself.net
Any other graphics not listed below were made by Dennis Payne. Those would be the really ugly ones. Much of the graphics listed below were also modified by Dennis Payne.
Mushrooms, star, coin, coin block animation, coin block and plant graphics came from Mario-like stuff by Kelvin Shadewing (http://kelvinshadewing.net)
Deathcap, Empress, and mushroom on flag came from Super-Guido by Kelvin Shadewing (http://kelvinshadewing.net)
Cannon Bob came from Cannon Bob by Kelvin Shadewing (http://kelvinshadewing.net)
Pipes came from 16 Bit Pipes by Kelvin Shadewing (http://kelvinshadewing.net)
Escarts, vines and bonus platform came from Monsterboy in Wonder World mockup assets by surt
Octafetch came from Random Ocean Creatures by RAPIDPUNCHES
Castle bricks, castle inside bricks and block debris came from RPG Tile Set 'Military Base' NES by Chasersgaming (https://chasersgaming.itch.io/)
Clouds came from Clouds and Gust by Urie W.
Tree tops came from Tiny Tree by Mirofox
White and green platforms came from Snow Tiles by Kelvin Shadewing (http://kelvinshadewing.net)
Block came from Square Block Textures by etqws3
Underwater block and coral came from Monkey Lad in Magical Planet by surt
Small and big player characters came from Super Miyamoto by Lars Doucet & Sean Choate
Cloud, water and lava blocks and Stormerin Escart came from Super Miyamoto Land Tilesets by Lars Doucet, Sean Choate, and Megan Bednarz
Fire Potion came from bubbling potion bottle by serenajeanne
Fireball came from Firebal 32x32 by MSavioti
Toad came from Mushroom, Dude by sparrow666
Viveva came from Fire by Spring Spring
Fire came from Animated Fires by stealthix
Many of these sounds were cut or altered for the game by Dennis Payne.
Overworld, underwater, underground, castle and level end music came from Hungry Dino (9 chiptune tracks, 10 SFX) by SketchyLogic
Stomp sound effect came from Fly Swatter Squish sound by qubodup
Star music came from At The Starting Line by Snabisch
Coin.ogg, vine, jump, swim, pause, shrink, mushroom eat, low time, fireball, boom, mushroom appear, one up, and pipe sound effects came from NES Sounds by Baŝto
Game Over sound effect came from Game Over 8bit music by 3DPyramid
Block break sound effect came from Sledgehammer - using to break a block of concrete. by Soundsnap
Block hit sound effect came from Plastic on bongos by remaxim
Death sound effect came from retro dead/destroyed/damaged sound by Prinsu-Kun
Drachtin fall, bridge break shot and Konami sound effects came from RPG Sound Pack by artisticdude
Castle end came from Victory! Composed by: Jon K. Fite
Intermission came form Fun Adventure by HitCtrl
Score ring came from GUI Sound Effects #4 by Jesús Lastra
Princess music came from End Credits Theme Music by Cleyton Kauffman - https://soundcloud.com/cleytonkauffman
Cannon Bob sound effect came from Cannon fire by Thimras
Fire sound effect came from Spell 4 (fire) by Bart K.
Portal enter, portal fizzle, portal1 open and portal2 open sound effects came from Spell Sounds Starter Pack by p0ss