On the most recent development update, it was announced in a tiny paragraph after showing off the new characters, that development of this game is due to be ceased indefinitely. The story mode, which was advertised in the Indiegogo campaign and was part of a stretch goal is now scrapped after years of being told it was coming and that development was being done. What a joke.
With the recent clearance and closure of Mane6's merch store, the lengthy wait for the second half of the season pass and lack of updates after the change of publisher, it was pretty obvious something was going on behind the scenes, and it shows. Most likely, this wasn't the fault of the developers, at least I'd like to imagine so, but possibly on the new publisher, Modus, and if so, I wish them the best with their future projects, however as it stands I don't believe I can recommend Them's Fightin' Herds any longer. Due to the development being halted and no doubt that the already small playerbase is going to drastically shrink in the coming months and years, I don't see the game's servers lasting long either.
This is an incredibly disappointing turn of events, as I feel this game had so much potential, so many interesting and fresh ideas for a fighting game, such an interesting cast of characters and world, and in the end it all got cut short before it could reach its true potential.

Snake: He survived by feeding on the blood of his family to quench his thirst. That was how he acquired a taste for blood...

Raiden: So that's why they call him "Vamp"....

Snake: No. "Vamp" isn't for vampire. It's because he's bisexual...

Not sure why they're charging £55 for this when it's a pretty bog standard 2D Sonic game, with no real identity of its own besides small little bits and pieces.
The game itself is fine, it controls well, looks nice enough and I really like Trip as a character, but it just has nothing over something like Mania which oozes style and personality, whilst Superstars honestly just feels like a new 2D Sonic game and not much else, with a lot of elements ripped straight out of Sonic Triple Trouble on the Gamegear.
The momentum is great, it's pretty much 1:1 with the original games, and the level design can be good... in the first half of the game. While not as bad as in the games developed by Dimps, the level design in the second half takes a nose dive and quickly becomes incredibly frustrating with a lot of questionable choices in how the layouts are approached.
There's a strong focus on 4-player co-op in Superstars and that's great, it could be the main thing carrying and excusing some of the lesser parts of the game, but I guess somebody at Sega decided online co-op would make too much sense for this game and threw it in the trash. Why? Why did they take the most defining element of the game, the thing they keep highlighting in the promotional material and relegate it to local only in a post-covid world? What was going through their mind when they made that decision? I'm just baffled by it.
With that said, probably the most disappointing aspect of the game would be the music. Some of it is genuinely nice to the ears but isn't all that memorable, and then there's the songs that sound as if they're ripped straight out of Sonic 4, that awful sound font and all. It isn't a great soundtrack, and that's probably the biggest sin you can commit in a Sonic The Hedgehog game.

Sonic Superstars can be easily described in one sentence and I mean this in the nicest of ways; This is the New Super Mario Bros of the Sonic franchise.

"So, what should we add this season?"
"Mud."
"Mud?"
"Mud."
"...Mud?"
"Mud."