Did you ever witness an impressive video game run that made you go "Wow! How is that even possible?" Amazing gaming feats that leave you stunned? If yes, post them here.

Rules:
Any video game type or genre is welcome however:
_ Please don't concentrate on speedruns. While I really love them, there are already enough sites dedicated to them. If the speedrun stands out in some way, by all means post them, but not if its only claim to fame is the fact that it was completed below n minutes.
_ Only gameplay related achievements, not hardware, metagame... etc. So while getting Doom to run on a pocket calculator, writing a Diablo clone in less than 20 bytes or creating a robot that can play Half-Life by itself are all very impressive, they don't really belong here.
_Obviously no cheating. It has to be a real gameplay, not something created in photoshop... etc.

As I've said in another thread: Human stupidity never ceases to amaze me, but neither does human ingenuity.


I'll start:
Here is completely functional brainfuck interpreter written in SpaceChem:
https://www.youtube.com/watch?v=EzzLzUCRmBw
Uses 4-bit cells. It almost blew my mind the first time I saw it.

Incidentally, it proves that SpaceChem, given infinite size, is Turing complete.
And makes me wonder how easy/hard it would be to simply simulate a Turing machine. There's an idea for something to do when being very bored...

I would have to say coding Flappy Bird into Super Mario World.

First link shows the end result, while the second video shows the process of actually achieving it. Would using an arbitrary code execution exploit in a game to inject Doom and run it count?

Edit: Here's another one: Beating Dragon Warrior, on a real console, in under an hour. What makes this speedrun interesting is the amount of RNG manipulation that had to be done to pull it off. (For anyone unfamiliar with the game, you normally need to spend hours leveling up to at least level 17 to learn Healmore to have a chance (I note that Hurt and Sleep almost never work on the final boss); this run beats the game at level 7.) https://www.youtube.com/watch?v=xswf_3ZD-1k

I figure this swordless run of The Legend of Zelda might qualify? At least I found it impressive skill-wise. When I heard about it for the first time, I was really intrigued: one of those things where you go, is that even possible? And as the runner mentions and you'll find out if you watch this, it both is and isn't. Makes for an entertaining example of being stubborn about wanting to play a game with your own rule set.

That reminds me: How about playing through part of Ocarina of Time while wearing a blindfold?
https://www.youtube.com/watch?v=IhHMW_atNG4

I haven't watched this video, but from what I have read, this shows not only what one can do, but also how good the sound design of the game is.

The blindfolded runs are really special. I recall that race of Mike Tyson's Punch-Out!! in that category. Quite an extraordinary accomplishment.

Dont know if this qualifies, but I once built a 5-bit decoder as a controller for a 32-track train switching system in Vanilla Minecraft. It's not nearly as impressive as the Brainfuck interpreter I know, but I was quite proud of it at the time.

Here's a guy who built a full-color 178x100 movie player in Factorio: https://forums.factorio.com/viewtopic.php?t=37490

The other sort of achievement I like is how people have been dissecting games to figure out how they work, allowing feats like the whole "Watch for Rolling Rocks" 0.5x A presses to be accomplished (albeit with tool assistance).

Among the games that have been heavily dissected are Super Mario World (to the point of Arbitrary Code Execution (ACE for short), Pokemon (ACE in the first three generations), and Super Mario 64 (involving things like parallel universes and even a demonstration of how floating point variables behave). Also, some Final Fantasy games have been dissected to the point where damage amounts can be calculated; this has led to observations like damage overflow (in FF6, level 99 + 140 Magic results in Ultima only doing a few hundred damage; in FF7, damage overflow allows Emerald Weapon to be killed in one hit) and even some major skips in some games (FF1 (JP) and FF2 both have ACE).

In all seriousness, it has gotten to the point where watching these videos can be quite educational; there's a nice Super Mario World Credits Warp Explained video on YouTube that gives insight on how one can trick a computer program into executing arbitrary code (the most severe type of security vulnerability).

Edit: Corrected name of the 0.5 A presses video.

There's a blind Street Fighter V pro

https://youtu.be/LJwe7uOmPJ0 You either Press A or you don't you can't 0.5 press it.

Super Mario Bros. - 500 Point Run

Pretty impressive indeed!

Actually, what is termed an A press is actually two events as far as a typical game program (or other GUI program, for that matter) is concerned. One event is when A is pressed, and the other is when A is released. In this case, I believe there is no A press during the level (A is being held down as the level is starting), but there is an A release, hence how the level can be done in half an A press.

Of course, in a full game run the A button would need to be pressed and held down before entering the level.

Continuously holding down A doesn't halve an A press. Even by strecthing the logic it would still be a 2/3 A press.

Beating the final boss in Rogue Legacy at level 0.

Insane if you ask me ;)

It may not get rid of the other half of the press, but it *does* move it to some other part of the run. In particular, one could press A and hold it down before entering the stage, and then release it during the stage; that's 1x A press, of which 0.5x occurred during the level.

Also, you *have* to admit that it was an impressive achievement, with all the parallel universe stuff going on.

(Of note, a slightly modified version of the route, which still goes to parallel universes, has been verified on console with the help of something like TASBot.)