This thread is intended for people looking for hints to any of the puzzles. All hints I'll post will be encoded using rot13. Regardless, avoid reading below if you don't want spoilers, as some information is not obfuscated well even with rot13.

This game does have a built-in hint system. Every 3 minutes (this value can be increased or decreased in the Options/Gameplay menu) a new note will be passed through the door, containing a hint for one of the puzzles you have left unsolved.

If you are posting hints for others, please be considerate and also encode your hints in some way so that people can choose whether to read them or not. Thanks!

For convenience, the hints are as follows (rot13 encoded, as mentioned above):

Favorite Phrase:

1. 2ERQ + 3TERRA + 3OYHR = 8
2. 01000001–01111010
3. Gur cvkryf ubyq gur yrggref.

Favorite Saying:

1. Gur obbxf ubyqf gur xrl.
2. Gur gehgu yvrf bayl va gur yrggref.
3. Hfr bayl gubfr jubfr cbfvgvbaf fgnaq ol bar naq gurzfryirf.
4. Oryynfb vf gb oynzr.
5. Nzrevpn'f Shgher. = ZRVNGE

Favorite Number:

1. Ahzoref jvguva ahzoref.
2. Cvpgherf jvguva fbhaqf.
3. Evpuneq Qnivq Wnzrf zvtug uryc lbh.

Favorite Song (Simplified puzzles and/or no hearing puzzles options on [the default]):

1. Gur zbavgbe ubyqf gur nafjre.
2. Gurer ner yrggref va gur cvpgherf.
3. Gur nafjre vf fgergpurq bhg.
4. Yrg gur oryy thvqr lbh gb gur fbyhgvba.
5. Qbg lbhe 'v'f naq qnfu lbhe 'g'f.

Favorite Song (Simplified puzzles and no hearing puzzles options off):

1. Yvfgra gb gur jnirf.
2. N GRZCRFG va n grnphc.
3. Lbhe zbavgbe jvyy gryy lbh gur nafjre.
4. Lbh arrq n enqvb.
5. Frnepu gur serdhrapvrf.

If you're still struggling after those hints, here are some examples of programs/webpages that could be useful:

Favorite Phrase:

• Zvpebfbsg Cnvag
• TVZC

Favorite Saying:

• uggcf://jjj.qpbqr.se/ra

Favorite Number:

• Nhqnpvgl

Favorite Song (Simplified puzzles and/or no hearing puzzles options on [the default]):

• Jvxvcrqvn

Favorite Song (Simplified puzzles and no hearing puzzles options off):

• N erny-yvsr NZ/SZ enqvb

Maybe instead of posting that and deleting the comments, which are supposed to be a feedback and help, you could have been more engaging with the community. See, that's the reason why your game won't be popular or played by many. It is not about the answers we were looking for, but how the gameplay felt. If someone tells me the answer straight away, then I lose interest. 
Just a rude gesture from you, that's all. Good day. 

i did the number and song puzzles but wanted to make sure im not barking up the wrong tree with the saying puzzle.

vg hfrf gur jnyy jevgvat naq obbx evtug?

That's correct.

If you're still having trouble with that puzzle, cnl nggragvba gb gur pubvpr bs jbeqf va gur svefg cntr, rfcrpvnyyl va pbawhapgvba jvgu gur ynfg uvag.

thnx. i didn't need the extra hint :)