-Dimensions? every game a world? 1 million copies, likely more.
-Need to find ways to check/contact others that might have done the same. Contact Toby?
-Are other games the same? Is this world a game?

-Show the other runs? LP maybe
-Can Flowey still reset?
-Gaster?

Your list looked manageable, which was surprising considering just the scope of what you were hoping to help with. You know there will be other things to add later but guess having a small list was less daunting right now. Honestly just having something written down that you could focus on was helping to keep you grounded as, well, everything was just a tiny bit crazy and impossible and did you mention CRAZY? You-you need to do SOMETHING so you don't feel like you have lost all grip on reality.

Breath. One step at a time. Focus on the list.

After a quick internal debate you decide to remove trying to contact Toby Fox. You had no idea how you could really get in contact with him properly…and even if you did there would be no way for you to not sound like some nutcase.

Then again maybe he was the one who made the worlds connect? He made the game after all, or at least claimed to have made the game…practically on his own. Hmm…That was something to put on the 'later pile' or maybe when you had run out of other options.

Sticking to what you know and have experienced yourself, the game clearly influenced Sans' world but it didn't seem to be the world itself. The fact it had continued to exist and move forward long after you had stopped playing, and even having your PC switched off, made that theory seem plausible.
That was a good start right? That meant that even if the game was deleted it shouldn't have an effect on the actual world…maybe. Not something you wanted to test but it was possible if Sans and Alphys could find a way to lock everyone out of playing Undertale…
No.
You sigh. There was no way that was going to work. Particularly with the game now being on so many systems.

So was each game its own world? Or at least each copy since it certainly didn't seem to be saves in particular with how things carried over. The problem was that that didn't make sense, not if the game could act independently, unless each time a new game was installed a new world was made. Ugh this was giving you a headache. None of this made any sense. It wasn't meant to make sense, it was a game. But now…Maybe you should wait till Sans gets back, at least then you could bounce ideas off each other instead of letting them just go round in circles in your head.

Breath, focus.

Okay, next point, was there a way you could find others that had done what you have done. You couldn't be the only one to have managed to link up with the game now that you knew it had been done once. The problem was that you had already searched for posts made by others about Sans getting in contact, and you had turned up diddly squat. Maybe some sort of code word then, something you could get from Sans that would let you search for others that managed to reach out. That could work. You add that to your list.

You look at your third entry '-Are other games the same? Is this world a game?' Nope, that's not something you want to unpack right now, and you don't think you will be ready to jump into a game for a while to say the least.
Since you don't know if you could even replicate what you had done here there was no point jumping down that rabbit hole. You remove that point from the list. In the end it didn't even matter if this was some sort of simulation, you would just keep living your life, that's what really mattered when it came down to it.

Now comes the moral dilemma, to show Sans, and likely Alphys, the other runs of the game. It made sense to make sure they had all of the info they needed, and it might even shed light on if each game was its own world or if it was some sort of collective. Maybe like 'Twitch plays pokemon'. Everyone entering their input and the most common is filtered into the world? That's certainly an idea and add it to the list, but was it worth the pain it might cause?

Going over it you don't think that any of them actually need to see a No Mercy run, you could just explain it, that should be good enough. As for other areas of the fandom, nope, you are not touching that with a ten foot barge pole. They had more than enough to sort out without putting any of those mental images in their heads, though Alphys might not complain. Maybe you could dig up some of the really nice fanart that had been made though, you bet there are some lovely ones of Undyne and Alphys together, clean of course. You're smiling without realising it, picturing their reaction.
Since your router is still turned off you decided you will just download the images to your phone and then upload from there. Sans had already shown they could access your PC whenever he wants, so long as it's on, so you would rather not risk it. Sans let loose on the internet would be a bad time for all. Mostly him.

Now onto the subject of Flowey, oh boy was that a lot to unpack. Sans needed to know about his resets, and if Alphys hadn't already told him what she did, well that was going to have to come out. This will have to be handled carefully.
Flowey, Asriel, the one bit of unfinished business. You knew you were not the only one who wanted a good ending for that kid. So many stories exploring the possibility. It's his abilities as Flowey that matter for this though. Could he still reset? Now he is likely the one with the strongest determination there was a chance for that, the last thing you needed was for all the progress you had made with Sans trusting you be completely ruined by a reset you were not in control of. Flowey might even be able to shed some light onto how it all works. After all, he talks to you when the game is over right? Then again so does Sans at times.

And then you come to the final point. This one was probably the biggest and most complex out of all of them. W.D Gaster. A character that is both in and not in the game. Who Sans may or may not remember. Hell, there was a high chance they were related.
But.
Was it even relevant? You KNOW the theories is that he is somehow scattered through time and space, likely with other monsters, but did that tie in with what was happening right now? Maybe? Maybe he was scattered through the code or void or whatever was connecting two realities. However you have to admit you mostly want to ask about Gaster to see Sans' reaction, see if he remembered him, but…what would be one hell of a question. Maybe you should start with the simpler questions and leads first. If things start pointing his way then you could bring him up. It's not like you had much information on him after all, it was mostly just speculation.

-Dimensions? every game a world? 1 million copies, likely more.
-Need to find ways to check/contact others that might have done the same. Get code word
-Twitch plays?

-Show the other runs? LP maybe
-Can Flowey still reset?

There, that was a solid list to bring up with Sans and Alphys and you had things you could work on yourself. This feels good, solid, manageable. Now you just need to wait for Sans to get back. Looking at the clock it's been over half an hour. Might as well get something to eat before catching up with other things. Your life had been turned on its head but that didn't stop your life from still being there and needing attention. If Sans could keep going knowing all of this, then you certainly could.