Rocket Robot on Wheels (Sucker Punch)
Sonic 1 (Sonic Team debut)
Shovel Knight (Yacht Club)
Halo: Combat Evolved (Bungie)
Spyro The Dragon (Insomiac)
Ty 1 (Chrome Studios)

I'd suggest Rocket: Robot on Wheels by Sucker Punch

Insomniac's first game was Disruptor) and not Spyro.
I don't think I've heard of anyone arguing that Rocket: Robot on Wheels is Sucker Punch's best game, at least not over Sly 2 or Ghost of Tsushima. I could be convinced though.
Bungie's first commercial game is [Operation: Desert Storm](https://en.wikipedia.org/wiki/Operation:Desert_Storm(video_game)), not Halo.
Good call on Sonic Team, can't believe I forgot that.
Sort of reluctant to include Yacht Club here since their main release is Shovel Knight, and the rest of their games so far have been spinoff games of Shovel Knight.
According to Wikipedia, Krome's first game was Mike Stewart's Pro Bodyboarding, so Ty the Tasmanian Tiger wouldn't count here.

Thanks for thinking up the suggestions!

In Rocket's defense I'd say 3d platformers were played out on ps2, but on n64 they were fresh and Rocket was top of the pile

Also would games that new teams made with existing IPs count such as evening star for sonic mania

To answer Speedy's question, yes, I think that would count, as long as the new teams had also made more than one game (otherwise we would have a lot of one game studios on the list).

Would Viewtiful Joe by Clover Studio count?

I was considering Viewtiful Joe for the list though there's some tough competition (God Hand & Okami). But it's a subjective list so, why not!

I believe Ubisoft Montpelier had their start with Rayman 1 though Rayman 1s quality can be disputed, Bandai Namco got their start with Pac Man and Junction Point with Epic Mickey

That's all i got now

Namco's first game appears to be Gee Bee) instead of Pac-Man.
I'm not sure if anyone else would argue that Rayman is Ubisoft Montepelier's best game over say, Rayman 2 or Beyond Good and Evil, but I'd be open to discussion.
Sort of reluctant to put on Junction Point since they've only made two games, and they're both Epic Mickey (sort of the same reason I didn't want to put on Dennaton since they've only made Hotline Miami 1 & 2). Thanks again for the suggestions regardless!

Treasure didnt make Alien soldier, both S&P, ikaruga and Radiant Silvergun to get disrespected like this

Blood by Monolith Productions.
The game that debuted the studio with former Apogee workers if I remember correctly.

@PostWar I did say arguably to be fair, so I'm more than happy to acknowledge that there is in fact plenty of reason to believe that Gunstar Heroes is not Treasure's best game. But I'm glad the discourse has been created!
@TheMatee Added Blood, thanks!

According to Yuji Naka, although Sonic 1 was the first time most of the team had formed to make a game, Sonic Team as a brand didn't form until NiGHTS into Dreams, which is also arguably their best game.

Xenogears for Monolithsoft

Could you make a list of the best game of each studio?

I'm not sure I have the expertise for that list right now admittingly, but perhaps someday!

Star Wars Knights Of The Old Republic 2 from Obsidian Entertainment, the best game from the Black Isle/Obsidian lineage and dare I say the only good Star Wars game.

Actually had a few more suggestions for this list:
Oddworld Abe's Odysee (Oddworld Inhabitants)
The Silver Case (Grasshopper Manufacture)
Kingdom Rush (Ironhide Game Studios)
System Shock 1 (Looking Glass Studios) and System Shock 2 (Irrational Games)
Arx Fatalis (Arkane Studios)
Fallout 2 (Black Isle Studios, when Fallout 1 released there was still no studio named Black Isle yet)
Arcanum: Of Steamworks and Magick Obscura (Troika Games)
The Elder Scrolls III Morrowind (Bethesda Games Studios)
Wolfenstein The New Order (MachineGames)
EYE Divine Cybermancy (Streum On Studio)
Deus Ex Human Revolution (Eidos Montreal)
Silent Hill 1 (Team Silent)

Just to name a few.

@Rogueliker Thanks for all the suggestions!

xenogears wasn't monolith, it was still developed in-house at square by the same product development team that would eventually work on chrono cross as well. monolith wasn't formed until late in 1999, with their debut title being xenosaga episode I a few years later

@theia You're right, looked more into it and deleted the entry. Thanks!

My recommendation is for Remember Me from Don't Nod. I know Life is Strange is more popular, but I prefer Remember Me to all their games afterwards. Though I haven't played Banishers yet.

I am curious why Morrowind is on the list. Didn't Bethesda make Elder Scrolls 1 & 2 prior to 3?

Thought I would pitch in:
Ico (Team Ico)
Gothic (Piranha Bytes)
Moon (Love-de-Lic)
Minecraft (Mojang Studios)

Good list, respect for Silent Hill 1. And thanks for a couple adds to this spiritually related list of mine

@LucasTheYeti @Consciovs Thanks for the suggestions, wanted to address a couple. Morrowind is on the list because it's Bethesda Game Studios (established in 2001) as opposed to Bethesda Softworks (established in 1986). Softworks developed Arena and Daggerfall, and Morrowind was the first project undertaken by Game Studios. Also, I left Ico off for now since while Ueda has directed three games, two of them were under Team ICO and the third, Last Guardian, is credited to his new studio GenDesign rather than Team ICO. A bit of a technicality, but Team ICO is only officially credited with Ico and Shadow of the Colossus so I think it's best not included for now.

@DJSCheddar Glad I could be of service. You can thank Rogueliker for the inclusion of original Silent Hill, though in fairness I find myself appreciating the original a ton more recently and it might end up becoming my favorite of the series with enough time.

had no idea how many fucking bangers there are, imo metroid prime is the most impressive. great list