The following users are those who have either deactivated their DeviantArt accounts, didn't post their contributions, or deleted their artwork since contributing to Project 20:

3VAD (contributed humanoid Sonic in bottom right corner, which is based off a Sonic CD Easter Egg)
AtsusaKaneytza
BladeSwipe (Omentis)
Bleeding-Fingertips
Blue-Chica
Creator-of-Scorch
ChenanaArts
ellavega
gamebuddy123
GsukiTsukenFunaga
Kehny
Ksarken
Lunavi9
marioking89 (submitted contributed image to DeviantArt profile, but image is disqualified from inclusion in Flashpoint due to being paid content)
MightyApplejacks
morak220
Nyanamo
Rabid-Noodles
rogferraz
sargemav352
ShadoHejjihoggu
Sonicmark
sonicspin2
Stephane-81
wooly-san
Zatic-The-Hedgehawg

The following are those who contributed to the project, but are assumed not to have DeviantArt profiles:

Abayxthehedgehog
Antanariva
brett nelson
ChaosChao83
ChaoticAngel09
Cornilieus
Darren_Price
DragonLight14
Goggle_Buster
hauken
Jack Sanders(FlazTheSundog)
Jorge-L.Gtz
kammie
Kez
Kitsune_Alchemist
prof zolo
segasonic
SonicEPICmaster
sonishi
Starway
SuperAaron360
tails523
Time8th-Ell_Shmell
Venom34
White Sonic
zep
ZZZororin