Hope this can help people looking to run the category, I have tried to put it into words to the best of my ability. I will probably make a video tutorial soon to show off some of the tricks and explain things better.
The Basics: Welcome to Mari0, a combination of Super Mario Bros and Portal. Although this game does appear to be simply Super Mario Bros with a portal gun, there are some noticeable differences in the physics and engine of the game. First off, Mario's jump appears to follow more of a evenly timed parabola shape, compared to NES where Mario has a seemingly slower uptime and a faster downtime. That may not make sense, but if you attempt to switch between the two there is a noticeable difference. This can cause getting a perfect stairs to be much harder than in NES. Second major difference, you are playing a Mario clone on a PC, so no enemies can be despawned or anything of that sort. I have not done any official timing, but from what I can tell hitting the top and bottom of the pole makes no difference as you wait for the flag anyways (feel free to test this and correct me with the numbers). As far as I can tell, frame rolls are nonexistent, so the level will be the same every time you play through it, minus Bullet Bills, Hammer Bros, and Bowser.
Notable things for the run include avoid fireworks at almost all costs. Fireworks can occur when you end a level with a 1, 3, or 6 on the last digit of the clock, and you will get that many fireworks respectively. For example, if you get a 335 on 4-1, you will save around 3 seconds when compared to a 336, even though you are slower by one in game second, you don't waste time on 6 fireworks. Another important technique to learn is portal running. It can be achieved by firing a portal ahead of you while jumping, then firing a portal below you to land in. This will cause you to move significantly faster in flat levels, as you teleport forward and maintain momentum. Also, in-game timers will be given in three digit numbers, RTA times will be given in a number of seconds. I will use these interchangeably as how I use them as indicators for good and bad sections of levels.
1-1: This is a fairly easy level, but somewhat difficult to get consistently good times. The only difficult part of the level is 3 portal jumps, and that can come with ease with practice. Fastest time for 1st pipe entry is 390, but a 389 is still okay. Hardest exit time of the underground is 387, which can only come with perfect movement and a 390 entry. 386 is a good underground exit. Best flag hit time is 380, which requires a perfect rest of the level, a 389 is still fairly hard to achieve. Shoot for around a 388 to 387. Without any portals this level can be completed at around a 375-380.
1-2: The second level of the game has threeish pathways that can be taken throughout the level. Method 1, the most difficult, is performing a one frame jump directly after the cut scene, on the first frame that you gain control of Mario, and making it to the top of the level. Method 2 is a different strategy to get to the top, fire a portal directly up and down on the edge, gain momentum then fire another portal next to yourself to fly to the top. For this you have to beat the Goombas, and make sure to cancel your portals so the Goombas don't follow. For Method 1 and 2, use portal running across the top to move quickly, and try to figure out a good number so you don't miss the elevator cycles near the end. In the warp zone room, fire a portal on the back wall and one below you. Be careful to fire the portal below you after you have hit the ground, or else your momentum will carry over and you will miss the pipe to World 4. Method 3 is just playing through the level normally, except for portals in the warp room. Overall Method 2 can save up to around 3 seconds over Method 3, Method 1 saves around 3.5 seconds over Method 2, and 6.5 seconds over Method 3.
4-1: This is a straight forward level once you master the two Piranha pipe jumps in the middle, each of which are about ten frame windows. Without portals this level will usually finish in a 336, so you save a lot of time if you wait an in-game second to hit a 335. One decent portal walk can have the level end in a 337-338, and more jumps means more time saved. This level isn't entirely flat, so be careful not to bonk on the blocks when coming out of the first portal fired. Portals save about one second overall if only one walk is used, more walks means more time saved.
4-2: This level is easy to mess up, and I know from experience. The first gap can be skipped by a fairly easy portal that can be lined up as you fall. Try not to bonk on the question mark blocks after the hallway, but it will usually happen. I have not found a way to wrong warp this level as seen in the NES, so we get to hit and climb the vine. (I believe this is due to it being on a PC not NES and you have the ability to move backwards in the level, but again, please prove me wrong and show me!) There are four hidden blocks underneath the vine that you need to hit. Personally I like to hit the left one coming off the elevator (this block is not needed), then go to the right one and move left for the last two. I have found the second and tallest block to best easiest to hit when you have the two blocks next to them hit first. The hitbox for the vine spawns immediately when you hit the block, but the sprite takes a little bit of time to catch up. This means just jump where the vine is going to be, even if its not there yet, and you will go up. The clock will stop once you hit the vine, the best time I've gotten is 373 but it can be better, anything higher than 370 is good. Once you get to the next room, firing a far portal and jumping can save some time, and then the warp room is the same as 1-2, warp to World 8.
8-1: As of the time of me writing this guide, this is the longest level, on average around 1:05 in total time. I would love to get this under a minute and I haven't gotten to grinding World 8 strats, so I'll just give some tips now and hope that others can help me optimize World 8 overall. Unfortunately, you cannot despawn any enemies like in the NES, so this level is somewhat different. No portals can really be used to save time that I have found, so its good old platforming that can save time. There are a couple pixels on Piranha pipes where they won't kill you, use them to hop over the pipes rather than waiting. I like to collect the star, as from I can tell it saves a little bit of time compared to waiting on the Piranhas and making the jumps over the Goombas. At the end you can jump over the last 3 Koopas at a percise time and miss the Piranha, and then just take the broken stairs and don't fall. For me, I would currently say a 167 or above is great, 163-165 is good, and below is not so good.
8-2: Yay the level I used to be decent at and now I suck at real hard for some reason. Again I have not completely optimized World 8, but a good run at this doesn't really have much that can be added. At the start make sure to take off right away and jump into the safe spot on the top of the bottom split of the stairs. As far as I can tell Bullet Bill firing is mostly RNG, but it is affected to some extent by your position compared to the launcher. I have not found anyway to make the part after the gap (the pits of death and despair, where runs go to die) consistent and good, so just hope for the best and don't get hit by the bullets. Recently anything above 300 has been good for me, but considering I have ten seconds to save from my gold split, just don't die and hope for the best. Again, no portals that I have found that save time here.
8-3: This level is honestly one of the easiest, but time can vary depending on Bullet Bill RNG. At the start, time a jump to hit the bullet that fires out of the second launcher (it is the same every time), and you can land on top of the launcher. If any bullets fire backwards towards you, you have to wait around 5-6 in-game seconds from when they pass the first pipe. Another difference in this game is that moving sprites don't despawn off screen, so that bullet is going until the end of the level. Another great thing is that you are slightly faster than the bullet, so you will run into it later on unless you wait the in game time. If you get not bullets that fire back, great! The rest of the level is just timing some jumps. The Hammer Bros have a 0% chance of jumping or throwing a killing hammer in the time it takes for you to pass them, so just keep running and jumping and you will be fine. This is always why I like making sure the bullet goes off screen, the Hammer Bros can jump while you deal with the bullet if they are on screen, and who knows what will happen. Again, no portal strats, and I feel like the level is fairly optimized.
8-4: This level I know for a fact can be optimized with portals more, so expect it to change when I figure out an optimal route, and hopefully others will help too. Like in 4-1, there is no way to wrong warp that I can find.
