Sonic Forces References

The game celebrated 25 years and also had some callbacks:


Words narrate the events, similar to the date/location given in SA2 cutscenes.

Eggman takes over the world while Sonic is away. This happened in Sonic the Comic and later in Sonic Chronicles: The Dark Brotherhood.

Eggman also took over in several other continues, but while Sonic was young, not missing. 

Knuckles leads the Resistance: a "rag-tag" team of fighters to "take back the planet." This group helps rescue Sonic after his 6-month capture.

This idea may have been inspired by:

• The (Knothole) Freedom Fighters, generally led by Sally Acorn in Sat Am and the Archie Comics. 
• The Freedom Fighters, founded by Sonic in Sonic the Comic. 
• The Resistance, the "underground" movement against Robotnik in Sonic Underground. 
• Team Hero, Sonic and his close friends who often fight Eggman in the games. 
• The Resistance, a group of humans that fought the Meterex in Sonic X. 

Green Hill, Chemical Plant, and the Death Egg all appear again.

This is the second anniversary game where Sonic fights Metal Sonic. 

Sonic says to Classic, "it's been generations since I've seen you," alluding to Sonic Generations.

Sonic's box artwork is similar to his art for Sonic Rivals 2.

Many trophy/achievement names are based on games/phrases.

The Avatar's clothing can reflect other characters (such as a Tails shirt with Knuckles' shoes or a chao backpack and Amy's boots).

Omega is broken down/out of commission for most of the game. Something similar happened in 06 as well as Sonic Chronicles.

Infinite refers to Sonic as a rat. This was something the Erazor Djinn often said in Sonic and the Secret Rings.

Shadow kicks Infinite in nearly the same way he kicks Silver in the head in 06.

The Shadow "replicas" mainly serve the same purpose as "Shadow Androids."

Episode Shadow has remixes from Sonic Adventure 2 and Shadow the Hedgehog. A part of "All Hail Shadow" can also be heard when he appears in the main story.

Update: How could I forget?! The US theme for Metal Sonic/Stardust Speedway Bad Future was also remixed! Sonic CD!

Rouge mentions an "intelligence division." This may implicate GUN.

Rouge tells Shadow "do it to it," which was a common phrase in the early cartoons.

Rouge indirectly mentions chilidogs.

Rouge also called Eggman "Rotton ol' Eggman." Even though she used to call him "doctor," I swear she's called him something like that before...