Man, if you want to know a VERY VVEEERY bad game from Sega...
...You need to know Sonic Eraser.
What is Sonic Eraser? It is an official game from Sega, and (maybe) the VERY first game Sonic is used as the protagonist.
It is a VERY obscure game even today, but I repeat, it is an official game, by SEGA.
Sonic Eraser is a Mega Drive game from 1991, and was released using the "Sega Game Toshokan" (
Sega Game Library), a download service for the Mega Drive (yes, a download service, for the Mega Drive, in 1991, by telephone line) using its Official Modem, only in Japan, years before the more famous "SEGA Channel". The "Toshokan" service distributed, basically, exclusive games, and very few commercial games you could get in a physical store (SEGA Channel, years later, will focus on distributing commercial games you could find in the stores).
So... in 1990 SEGA created the Mega Drive official modem, the "Mega Modem", an add-on you only can use in your Mega Drive... if you have the original internal board of that system, or maybe one of the very first revisions of the Mega Drive Model 1 board. Not ANY Mega Drive Model 1 is compatible with the modem: you need an old Model 1. Why? because Sega just cut costs and eliminated the port to connect the modem... around 1992, or maybe late 1991.
The port for the modem was, in those old models, behind the console (behind, NOT under), and is basically a female DE-9, like the 2 controller ports of the MD are... but this one, being "female" instead of "male" (probably to avoid some players trying to connect one controller in it).
Using the modem, along a "Special" cart (which basically seems a normal japanese MD cart) and paying a subscription, you could LITERALLY download games to that cart, and your MD play them as normal games. Being all of this in 1990-1992 (maybe including some 1993), 1 simple MB was a lot of data to download (using expensive telephone calls to some server of SEGA), so originally the games were not very big, and that means they were simpler games (I do not remember well, but I would say all Toshokan "exclusive games" weight less than 1MB or even less than 512KB).
Anyways, Sonic Eraser (apparently) was one of those games you could download, and it has one of the WORST music I've ever seen in a game. The game itself? is just a crappy puzzle game, a "Tetris/Columns" mix clone, but very bad. It uses two "Sonic 1" sprites, which appear all the time and SOMETIMES (sometimes... meaning almost never) react to what is happening, "fighting" against each other. The game never had a physical release, but you can find the rom, and play it.
The existence of this game was not "discovered" by the western public, until 2004, many years after its release, only because then, SEGA re-offered the game in some kind of "pay-per-play Mega Drive games service" (only in Japan), using its website and a "hidden" emulator. Some western user discovered this game in the catalogue of this service, and decrypted the rom (the games of the service were encrypted), "liberating" it.
It also seems SEGA thought, at some point, to include this rare game in the "Sonic Gems Collection" around that same era, in 2005, as one of the extra games... but they finally didn't (internal files of the compilation shows some references to Sonic Eraser).
It is, apparently (although it's not 100% clear to me) the very first game you can "play" with Sonic, because it seems Sonic 1 was not still in the market (but... I don't know if this is 100% sure. Sonic 1 was released in Europe and US in June 1991, and it is not clear when Sonic Eraser was "downlodable" from Toshokan, that same year).
It is NOT the first game you can see Sonic, for sure, because that game is "Rad Mobile" a "superscaler" arcade racer game released by SEGA, in the arcades, some months earlier in 1990, which have some little "Sonic doll" hanging from the rearview mirror of your car, as pure decoration.
If you have a Genesis/MD, and an Everdrive or similar, you can play this and other "Toshokan" games in real hardware. Many of them are mediocre games (they are basically like little demos), but boy, Sonic Eraser is one of the worst. I don't know if all of those games were preserved, but a lot of them are, because later, SEGA sold many of them in 2 compilations for Mega-CD, both sold inside metallic cans (nice cans, in fact), and another compilation for Mega Drive, this being exclusive for the japanese "Sega Channel" (this MD version apparently was also included in the japanese version of the Mega Drive 2 Mini, few years ago).
But they never included "Sonic Eraser", so, it was not until 2004 when "some western guy" discovered the game to the rest of the world.
The music of the game is fucking HORRIBLE.
The game? also horrible.