Third-party T-series codes

When Sega was producing video game hardware, the company used T-series codes to identify officially licensed third party publishers for its systems. T-series codes typically appear on the boxes and/or media of third-party Sega software, in a similar manner to how official G-series or MK-series identifers are displayed.

T-series codes came into use during the late 1980s and were issued until the mid-2000s. Prior to this there were relatively few third-party publishers and no official identification system - Sega typically published all SG-1000 and Sega Master System games (notable exceptions include Salio and various Western companies involved in SC-3000 development), however this changed by the release of the Sega Mega Drive. The first T-series codes appeared publically in 1989.

The first two (or three) digits after the T represent the publisher. Any numbers after this represent the specific release, and a letter on the end specifies a console (the latter not coming into use until the mid-90s).

Not all publishers followed these rules, most notably Electronic Arts which did not show its T-series code on Mega Drive releases.

Within games

Mega Drive ROM headers of games developed by a third party (except those that Sega contracts out, such as Nextech) usually contain a field stating the T-series code. For example, the sixteen bytes at offset $110 (hex) of game ROMs would usually look like one of

(C)SEGA year.mon
(C)T-xx year.mon
(C)T-xxxyear.mon
(C)Txxx year.mon

Not all third party developers/publishers have followed these rules; for example, Psygnosis, Kaneko, Taito, and Treco have placed their company name in the field on several occasions.

List

T-Code	Company
T-11	Taito
T-12	Capcom
T-13	Data East
T-14	Namco
T-15	Sunsoft
T-16	Ma-Ba
T-17	Dempa
T-18	Technosoft
T-20	Asmik
T-20	Asmik Ace Entertainment
T-21	ASCII
T-22	Micronet
T-23	VIC Tokai
T-24	Sammy
T-24	Treco
T-25	Nippon Computer Systems
T-26	Sigma
T-27	Toho
T-28	HOT-B
T-29	Kyugo
T-30	Video System
T-31	SNK
T-32	Wolf Team
T-33	Kaneko
T-33	Kaneko USA
T-34	DreamWorks
T-35	Seismic Software
T-36	Tecmo
T-40	Toaplan
T-41	UNIPACC
T-42	UPL
T-43	Human
T-44	Sanritsu
T-44	SIMS
T-45	Game Arts
T-46	Kodansha Research Institute
T-47	Sage's Creation
T-48	Tengen
T-48	Time Warner Interactive
T-49	Nihon Telenet
T-49	Micro World
T-50	Electronic Arts
T-51	Microcabin
T-52	SystemSoft Alpha
T-53	Riverhillsoft
T-54	Face
T-55	Nuvision Entertainment
T-56	RazorSoft
T-57	Jaleco
T-58	Visco
T-60	Victor Musical Industries
T-60	Victor Entertainment
T-60	Victor Soft
T-61	Wonder Amusement Studio
T-62	Sony Imagesoft
T-63	Toshiba EMI
T-64	Information Global Service
T-65	Tsukuda Original
T-66	Compile
T-67	Magical
T-68	CSK Research Institute
T-69	Arena Entertainment
T-70	Virgin Interactive
T-71	Nihon Bussan
T-72	Varie
T-73	Coconuts Japan
T-73	Soft Vision
T-74	PALSOFT
T-75	Pony Canyon
T-76	Koei
T-77	Takeru
T-79	U.S. Gold
T-81	Acclaim Entertainment
T-81	Flying Edge
T-83	GameTek
T-84	Datawest
T-85	PCM Complete
T-86	Absolute Entertainment
T-87	The Software Toolworks
T-87	Mindscape
T-88	Domark
T-89	Parker Brothers
T-91	Pack-In-Video
T-91	Victor Interactive Software
T-92	Polydor
T-93	Sony Electronic Publishing
T-95	Konami
T-97	Tradewest
T-97	Williams Entertainment
T-97	Midway Home Entertainment
T-99	Success
T-100	THQ
T-100	Black Pearl Software
T-101	TecMagik Entertainment
T-103	Takara
T-104	MicroProse
T-105	Shogakukan Production
T-106	Electronic Arts Victor
T-107	Electro Brain
T-109	Saddleback Graphics
T-110	Dynamix
T-111	American Laser Games
T-112	Hi-Tech Expressions
T-113	Psygnosis
T-114	T&E Soft
T-115	Core Design
T-118	Compton's NewMedia
T-119	Accolade
T-120	Codemasters
T-121	ReadySoft
T-122	HeartBeat Corporation
T-123	Gremlin Interactive
T-124	Spectrum HoloByte
T-125	Interplay
T-126	Maxis
T-127	Working Designs
T-130	Activision
T-132	Playmates Interactive Entertainment
T-133	Bandai
T-135	Capitol Disc Interactive
T-137	ASC Games
T-139	Viacom New Media
T-141	Toei Video
T-143	Hudson Soft
T-144	Atlus
T-145	Sony Music Entertainment Japan
T-147	Sansan
T-149	Nissho Iwai Infocom
T-150	Imadio
T-150	Imagineer
T-151	Infogrames
T-152	Davidson & Associates
T-153	Rocket Science Games
T-154	Technōs Japan
T-157	Angel
T-159	Crystal Dynamics
T-160	Sales Curve Interactive
T-161	Fox Interactive
T-162	Digital Pictures
T-164	Ocean Software
T-165	Seta
T-166	Altron
T-167	ASK Kodansha
T-168	Athena
T-169	Gakken
T-170	General Entertainment
T-174	Glams
T-176	ASCII Something Good
T-177	Ubisoft
T-178	Hitachi
T-180	BMG Japan
T-180	BMG Interactive
T-181	Obunsha
T-182	Thinking Cap
T-185	Gaga Communications
T-186	SoftBank
T-187	Pionesoft
T-187	Naxat Soft
T-188	Spike
T-188	MAXBET
T-189	KAZe
T-193	Sega Yonezawa
T-194	We Net
T-195	Datam Polystar
T-197	KID
T-198	Epoch
T-199	Ving
T-200	Yoshimoto Kogyo
T-201	NEC Interchannel
T-202	Sonnet Computer Entertainment
T-203	Game Studio
T-204	Psikyo
T-205	Media Entertainment
T-206	Banpresto
T-207	Ecseco Development
T-208	Bullet-Proof Software
T-209	Sieg
T-210	Yanoman
T-212	Oz Club
T-213	Nihon Create
T-214	Media Rings Corporation
T-215	Shoeisha
T-216	OPeNBooK
T-217	Hakuhodo
T-218	Aroma
T-219	Societa Daikanyama
T-219	Societa
T-220	Arc System Works
T-221	Climax Entertainment
T-222	Pioneer
T-223	Tokuma Shoten
T-224	I'MAX
T-226	Shogakukan
T-227	Vantan International
T-229	Titus
T-230	LucasArts
T-231	Pai
T-232	Reindeer
T-232	Ecole Software
T-233	Nayuta
T-234	Bandai Visual
T-235	Quintet
T-239	Disney Interactive
T-240	OPeNBooK9003
T-240	9003
T-241	Multisoft
T-242	Sky Think System
T-243	OCC
T-246	Increment P
T-249	King Records
T-250	Fun House
T-251	Patra
T-252	Inner Brain
T-253	Make Software
T-254	GT Interactive Software
T-255	Kodansha
T-255	Hakusensha
T-257	Clef
T-259	C-Seven
T-260	Fujitsu Parex
T-261	Xing Entertainment
T-264	Media Quest
T-267	Bethesda Softworks
T-268	Wooyoung System
T-270	Nihon System
T-271	Scholar
T-273	Datt Japan
T-278	MediaWorks
T-279	Kadokawa Shoten
T-280	Elf
T-282	Tomy
T-289	KSS
T-290	Mainichi Communications
T-291	Warashi
T-292	Metro Corporation
T-293	Sai-Mate
T-294	Kokopeli Digital Studios
T-296	Planning Office Wada
T-297	Telstar Electronic Studios
T-300	Kumon Publishing
T-300	Warp
T-303	Masudaya
T-306	Soft Office
T-307	Empire Interactive
T-308	Genki
T-308	Sada Soft
T-309	Neverland
T-310	Shar Rock
T-311	Natsume
T-312	Nexus Interact
T-313	Aplix Corporation
T-314	Omiya Soft
T-315	JVC
T-316	Zoom
T-321	TEN Institute
T-322	Fujitsu
T-325	TGL
T-326	Red Entertainment
T-328	Waka Manufacturing
T-329	Treasure
T-330	Tokuma Shoten Intermedia
T-331	Sonic! Software Planning
T-339	Sting
T-340	Chunsoft
T-341	Syn Sophia
T-342	From Software
T-346	Daiki
T-348	Aspect
T-350	Micro Vision
T-351	Gainax
T-354	FortyFive
T-355	Enix
T-356	Ray Corporation
T-357	Tonkin House
T-360	Outrigger
T-361	B-Factory
T-362	Layup
T-363	Axela
T-364	WorkJam
T-365	Nihon Syscom
T-367	FOG
T-368	Eidos Interactive
T-369	UEP Systems
T-370	Shouei System
T-371	GMF
T-373	ADK
T-374	Softstar Entertainment
T-375	Nexton
T-376	Denshi Media Services
T-379	Takuyo
T-380	Starlight Marry
T-381	Crystal Vision
T-382	Kamata and Partners
T-383	AquaPlus
T-384	Media Gallop
T-385	Culture Brain
T-386	Locus
T-387	Entertainment Software Publishing
T-388	NEC Home Electronics
T-390	Pulse Interactive
T-391	Random House
T-394	Vivarium
T-395	Studio Mebius
T-396	Panther Software
T-397	TBS
T-398	NetVillage
T-400	Noisia
T-400	Vision
T-401	Shangri-La
T-402	Crave Entertainment
T-403	Metro3D
T-404	Majesco Entertainment
T-405	Take-Two Interactive
T-406	Hasbro Interactive
T-407	Rage Games
T-408	Marvelous Entertainment
T-409	Bottom Up
T-410	Daikoku Denki
T-411	Sunrise Interactive
T-412	Bimboosoft
T-413	U.F.O. Interactive
T-414	Mattel Interactive
T-415	CaramelPot
T-416	Vatical Entertainment
T-417	Ripcord Games
T-418	Sega Toys
T-419	Gathering of Developers
T-421	Rockstar Games
T-422	Winkysoft
T-423	CyberFront
T-424	DaZZ
T-428	Kobi
T-429	Fujicom
T-433	Real Vision
T-434	Visit
T-435	Global A Entertainment
T-438	Studio Wonder Effect
T-439	Media Factory
T-443	Agetec
T-444	Abel
T-445	Softmax
T-446	Isao
T-447	Kool Kizz
T-448	GeneX
T-449	Xicat Interactive
T-450	Swing! Entertainment
T-451	Yuke's
T-454	AAA Game
T-455	TV Asahi
T-456	Crazy Games
T-457	Atmark
T-458	Hackberry
T-460	AIA
T-461	Starfish-SD
T-462	Idea Factory
T-463	Broccoli
T-465	PrincessSoft
T-466	Bigben Interactive
T-467	G.rev
T-469	Symbio Planning
T-471	Alchemist
T-473	SNK Playmore
T-474	D3Publisher
T-475	Rain Software
T-476	Good Navigate
T-477	Alfa System
T-478	Milestone
T-479	Triangle Service

Others

T-Code	Publisher (Label/Team/Alias)
T-38	Mediagenic? (only found in the ROM header for Fatman, which was published by Sanritsu (T-44))
T-172	EA Sports? (later EA Sports Mega Drive titles have T-172 serial numbers in their ROM headers...)