There is some paper taped to the door in Room 10:
Well done! You are now halfway! To mark this event, this cipher is EXTRA hard!
You then look at the main paper
To decrypt the first cipher, I've given you a mathematical equation:
$d(x) = a-1(x - b) \mod\ m$
a is 11, b is 25, and d is the decrypted text.
Izea ahx lprp z cjrqg hjay mx rdrp, kla ja pazeap hjay nexmp.
mmking solves it without dying, so you get to Part 2:
Everyone loves a mime. MDEwMDEwMDAwMTAwMDAxMDEwMTAwMDAxMDAwMTExMDAxMDE= The other key is key. Wmb wmmuh, drh imqfo tdvw ubonbv lcfkmod rr d vdqirp vrzugb isu bbd jbqbvdwmsr, fqh nv kmvwxfooc xrgudgbdgoc. Jr wr qc kbgwnwb, kmwmx pc rdpb. Wmbub, csx empo imqi wlb frwkbv.
PART TWO - HINT ONE
'My name' refers to something recent in The Twenty Doors series, but not this part. Go back through each one, see if you can find something useful...
As requested, here is the contents of the site page.
My name again. J2I. Pga torooapr fpi Rlis Mcrcl ym otmplx tv Gsic 10. Iepzve aud hb, cap pbqi hb dnui ub. Befud. I hate vowles, exept for i.
CodeNewbie is still working on getting at the password, but here is the ciphertext:
Also, like magic, a keyboard appears, with the letters A to Z on it!
PART 3 - HINT 1
! Spinny! @HHF G L\NFHP301 3@WDXECT R1T0||0T GTFDHPSRX5R 3ARHCU/ £A NT S0! If you can be bothered to decode that, you've then got to work out my L3etspeak. :) It's Markdown O'clock!
PART 3 - HINT 2
L3etspeak is usually written with two three's (L33tspeak). So, what could that three mean???
There are going to be three separate parts to Room 10, thus it is a semi-interactive puzzle. The next part will be added when this door is solved!