So, now that the dust has settled... here's all the new stuff on http://deltarune.com. Heading to the Sweepstakes page, you can find a link to http://deltarune.com/sweepstak... showing that alternate ending... a link at the bottom titled "WHAT'S NEXT?" leads to /ramb. (1/?)
In /ramb, clicking the parlor area now leads to http://deltarune.com/romb. The header says "No one will shed a tear for him." There's a door. When you click it, it opens and you'll have a brief period of time to click an invisible object moving in an infinity symbol...
...that ascends when clicked, plays the new "ma" sfx, changes the header to "You can never defeat us!! Let's rumble!", and leads to http://deltarune.com/chapter3. If you don't click it in time, you get the message below. Clicking the two blank spaces plays the "ma" sfx.
/chapter3 is also reached through the regular /sweepstakes page, which has a new "What's next?" link at the bottom. The header is just "..." and the next says "Not applicable." Holding the left arrow key makes the text "But..." slide in.
http://deltarune.com/chapter1 says "Not applicable." without any sliding text. http://deltarune.com/chapter2 says "Applicable." http://deltarune.com/chapter5 has the header "back" numbers below. 1 is tiny and invisible, 3 is large and invisible. Clicking on 2 plays "d" (Berdly's Snowgrave sfx) ...
Clicking on 3 plays "ma", clicking on 5 plays "h", and clicking on 4 leads to http://deltarune.com/chapter4. /chapter4 is blank, but a red pixel fades into view. Clicking it leads to http://deltarune.com/chapter4/... At /message, the same red dot appears and links to /message again, but...
Symbols at the bottom can be clicked to play "m" and "e" sound effects. Correlating the symbols to a standard qwerty keyboard, the "m" keys produce the letters "tyuoahkn," or "thankyou" rearranged. http://deltarune.com/chapter4/... is the end of this chain.
The header reads "How long did it take her to smile?" and there are two text prompts and a button. By default, clicking the button makes the text "Unknown contact" appear. Entering an email address and nothing in the second box makes "She never smiled?" appear.
Entering an email and something in the second box makes the text "Thank you." appear and all fields disappear, so this may be some kind of mailing list. On http://deltarune.com/egg, there is a new link leading to http://deltarune.com/rain, shown below.
That new link itself contains a link to http://deltarune.com/rarecats, a game about clicking cats for points. In addition to some cats having aura, an angel cat will spawn a window that leads to http://deltarune.com/windows, and DEVICE_FRIEND alsos jumpscare you and reverts you to homepage.
...based on RNG, that is. /windows is a long series of windows with URLs that all don't work. The header says "Aren't you forgetting something?" However, if you unscramble the URLs, you get the URL http://deltarune.com/lostwhere... On /lostwheretheforestwould grow, there's...
...a tree, and the header "ROOTS". Clicking the three three times plays a chord each time, and the fourth leads to http://deltarune.com/window. /window is nearly identical to /windows, but the URLs are all different. Descrambling the URLs again, you get http://deltarune.com/thepoorch...
At /thepoorchildren, the header says therapy and you can draw freely. Continuing to draw for a while makes the Chapter 1 Scarlet tree appear in the center once you draw over that area, and clicking it leads back to /egg. This seems to be the end of the chain.
UPDATES: - I was wrong, both /windows and /window have a slightly different window that leads to the unscrambled link. - The /code page has the page count updated from 26 to 40. - /chapter4/thankyou seems to no longer be accepting new emails and just says "Thank you" now.
UPDATES: I just got sent a weird blank email.
Apparently if you answered the second box with a number, your email would say "You answered [number] seconds." I never tried this, so mine's blank...