'Super Infiniboss: The Gauntlet' (2024) by happygreenfairy (Original Demo)
An endless boss battle arcade platformer. It's about you, an ever-changing boss, and tons of projectiles.
#NonSonicWeekend
https://sonicfangameshq.com/forums/showcase/super-infiniboss-the-gauntlet-sage-2024-demo.2232/

'Megaman X Omega Blaster - Definitive Edition' (2024) by Corrupião Lendário (Demo)
An Arcade/Arena style fangame inspired by the earlier MegaMan arcde games, but focused on the X sag.
#NonSonicWeekend
https://sonicfangameshq.com/forums/showcase/megaman-x-omega-blaster-definitive-edition.2042/

'Agent Stone' (2023) by HazelSpooder (S3Air Mod)
Agent Stone has became loyal to the evil Dr. Robotnik, and will do anything he can to assist him in repowering the Death Egg.
https://shc.zone/entries/contest2023/802

'Sonic Infinity+' (2020) by @SonicInfinity2 (Demo)
https://gamejolt.com/games/Sonic-InfinityPlus/440246

'Chaotix Mania' (2020) by Xanman (Mania Mod)
Brings the stages of the 32x game to 'Sonic Mania'. Part of the @SAGExpo for the year.
https://gamebanana.com/wips/50148

'Sonic - Frame By Frame' (2022) by @GameKidsFran (Demo)
Sonic runs automatically and you jump and roll to dodge enemies and obstacles!
https://www.sonicfangameshq.com/forums/showcase/sonic-frame-by-frame-demo.1480/

'Sonic X-Plosiv' (2004) by Assassin Games (Demo)
https://archive.org/details/sonic-xplosiv-01

'Sonic: Project Mettrix' (2001) by Organized Chaos (@HCStealth) (Demo)
The precursor engine developed by Organized Chaos. These learnings helped develop 'Sonic Mania'.
https://archive.org/details/mettrix

'Spyro Triple Pack' (2023) by Jesus_PK (SADX Mod)
Brings Town Square, Gnorc Cave & Tree Tops from 'Spyro' to 'Sonic Adventure', replacing respective stages, and playable with multiple characters!
https://shc.zone/entries/contest2023/894

'Sonic: Tennis For Two' (1999) by E-107 Theta
https://archive.org/details/tf2_20190916