Third-party T-series codes

Sega used T-series codes to identify officially licensed third party developers. 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 Sega Mega Drive 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.

T-Code	Developer
T-11	Taito
T-12	Capcom
T-13	Data East
T-14	Namco
T-15	Sunsoft
T-16	Bandai, Ma-Ba
T-17	Dempa
T-18	Tecno Soft
T-19	Tecno Soft
T-20	Asmik
T-21	ASCII
T-22	Micronet
T-23	Vic Tokai
T-24	Treco/Sammy
T-25	NCS/Masaya
T-26	Sigma Enterprises
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-34	DreamWorks
T-35	Seismic, Compile
T-36	Tecmo
T-37
T-38	Sanritsu
T-39
T-40	Toaplan
T-41	UNIPACC
T-42	UPL
T-43	Human
T-44	Sanritsu/SIMS
T-45	Game Arts
T-46	Kodansha
T-47	Sage's Creation
T-48	Tengen, Time Warner Interactive
T-49	Telenet Japan
T-50	Electronic Arts
T-51	Microcabin
T-52	SystemSoft
T-53	Riverhillsoft
T-54	Face
T-55	Nuvision
T-56	Razorsoft
T-57	Jaleco
T-58	Visco
T-59
T-60	Victor Musical Industries/Victor Entertainment/Victor Soft
T-61	Wonder Amusement Studio
T-62	Sony Imagesoft
T-63	Toshiba EMI/TAMTAM/System Soft
T-64	IGS > Data West
T-65	Tsukuda Ideal (Tsukuda Original (TODO confirm))
T-66	Compile
T-67	Magical
T-68	CSK Research Institute (CRI)
T-69	Arena
T-70	Virgin Interactive
T-71	Nihon Bussan (Nichibutsu)
T-72	Varie
T-73	Coconuts Japan
T-74	PALSOFT/Soft Vision
T-75	Pony Canyon
T-76	Koei
T-77	Sur De Wave
T-79	U.S. Gold
T-81	Flying Edge/Acclaim
T-83	GameTek
T-84	GameTek
T-85	PCM Complete
T-86	Absolute Entertainment
T-87	Mindscape/Software Toolworks
T-88	Domark
T-89	Parker Brothers
T-91	Pack-In-Video/Pack-In-Soft/Victor Soft/Victor Interactive Software
T-92	Sandstorm > Polydor K.K.
T-93	Sony
T-95	Konami
T-97	Tradewest
T-99	Success
T-100	Black Pearl Software (later THQ)
T-101	TecMagik
T-103	Takara
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 New Media
T-119	Accolade
T-120	Codemasters
T-121	ReadySoft
T-123	Gremlin Interactive
T-124	Spectrum Holobyte
T-125	Interplay
T-126	Maxis
T-127	Working Designs
T-130	Activision
T-132	Shiny & Playmates
T-133	Bandai
T-135	CapDisc
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
T-146	Takara
T-147	Sansan
T-149	Infocom
T-150	Imagineer
T-151	Infogrames
T-152	Davidson & Associates
T-153	Rocket Science Games
T-154	Technos Japan
T-157	Angel
T-158	Mindscape
T-159	BMG Victor, Crystal Dynamics
T-160	Time Warner Interactive
T-161	Fox Interactive
T-162	Digital Pictures
T-164	Ocean
T-165	Seta
T-166	Altron
T-167	ASK Kodansha
T-168	Athena
T-170	General Entertainment (GE)
T-174	Glams
T-176	ASCII Something Good
T-177	Ubisoft
T-178	Hitachi
T-180	BMG Japan
T-185	Gaga Communications
T-186	Game Bank, Soft Bank
T-187	Naxat Soft > Pionesoft
T-188	Mizuki > Maxbet > Spike, Geo
T-189	KAZe
T-194	We Net
T-195	Datam Polystar
T-197	KID (Kindle Imagine Develop)
T-198	Epoch/Sakata SAS
T-199	Ving
T-200	Yoshimoto Kogyo
T-201	NEC Interchannel/InterChannel
T-202	Sonnet Computer Entertainment/Varie
T-203	Game Studio
T-204	Psikyo
T-205	Media Entertainment
T-206	Banpresto
T-207	Ecseco Development
T-208	Bullet Proof Software (BPS)/Elorg
T-209	SIEG/PRISM
T-210	Yanoman Games
T-212	Oz Club
T-213	Nihon Create
T-214	Media Rings
T-215	Shoeisha
T-216	Open Book
T-217	Hamlet/Hakuhodo
T-218	Yumedia (Aroma)
T-219	Societa Daikanyama
T-220	Arc System Works
T-221	Climax Entertainment
T-222	Pioneer LDC
T-223	Tokuma Shoten
T-224	I'MAX
T-227	Vantan International/Electric Dreams
T-229	Titus
T-230	LucasArts
T-231	Pai
T-232	Ecole > Reindeer
T-234	Bandai Visual
T-235	Quintet
T-239	Disney Interactive
T-240	9003 > OpenBook9003
T-241	Multisoft/Millenium Interactive
T-242	Sky Think System
T-243	OCC
T-246	INCREMENT P (iPC)
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-257	Clef
T-259	Sega (? - Cleaning Kit)
T-260	Fujitsu Parex/JAPAN MEDIA PROGRAMMING (JAMP)
T-261	Xing Entertainment
T-264	Media Quest
T-268	WOOYOUNG
T-270	Nihon System
T-271	Virgin Interactive Entertainment, SCHOLAR
T-273	Datt Japan
T-278	MediaWorks
T-279	Kadokawa Shoten
T-280	Elf
T-282	Tomy
T-289	KSS/media muse, OPEN SESAME
T-290	MYCOM (Mainichi Communications)
T-291	Warashi
T-292	Metro
T-293	SAI-MATE
T-294	Kokopeli Digital Studios
T-296	BMG Victor/Planning Office WADA (pow)
T-297	Telstar
T-300	WARP
T-301
T-302
T-303	Masudaya
T-304
T-305
T-306	SoftOffice
T-307	Empire Interactive
T-308	Sada Soft (Genki)
T-309	Never Land Company/ESP (used only for Senkutsu Katsuryuu Taisen Chaos Seed, and I can't find any other Never Land game for a Sega system so)
T-310	Shar Rock
T-311	Jaleco, Natsume
T-312	NEXUS INTERACT/DaZZ, ISCO, Digital weare
T-313	Aplix
T-314	Omiya Soft
T-315	JVC
T-316	Zoom
T-317
T-318
T-319
T-320
T-321	Ten
T-322	FUJITSU/Digital weare
T-323
T-324
T-325	TGL (TECHNICAL GROUP LABORATORY)
T-326	RED/SIMS
T-327
T-328	Waka Manufacturing
T-329	Treasure/ESP (appears to only have been used for the Sega Saturn releases of Silhouette Mirage and Radiant Silvergun, with Ikaruga and Bangai-O being given ESP numbers despite being Treasure/ESP)
T-330	Tokuma Shoten Intermedia
T-331	Camelot
T-332
T-333
T-334
T-335
T-336
T-337
T-338
T-339	Sting/ESP (appears to have only been used for Baroque, with a Sega/ESP/Sting Dreamcast game being given a ESP number)
T-340	Chunsoft
T-341	Aki
T-342	From Software
T-343
T-344
T-345
T-346	Daiki
T-347
T-348	Aspect
T-349
T-350	MiCROViSion
T-351	Gainax
T-352
T-353
T-354	FortyFive (45XLV)
T-355	Enix
T-356	Ray
T-357	TONKINHOUSE
T-358
T-359
T-360	OUTRIGGER/Infini Entertainment Technology/Sierra
T-361	BANDAI VISUAL, B-factory
T-362	Lay-up
T-363	AXELA/BREAK
T-364	WorkJam (DIGITAL TOKYO, PLANPLAN)
T-365	Nsyscom > Syscom Entertainment
T-366
T-367	Full On Games
T-368	Eidos
T-369	UEP-System
T-370	Shouei System > Xuse
T-371	GMF/Falcom
T-372
T-373	ADK/SNK
T-374	SOFTSTAR ENTERTAINMENT
T-375	Nexton
T-376	Denshi Media Services
T-377
T-378
T-379	Takuyo
T-380	Starlight Marry
T-381	CRYSTAL VISION/Scoop
T-382	K and P
T-383	AquaPlus
T-384	Media Gallop/K and P
T-385	Culture Brain
T-386	LOCUS/SOLITON SOFTWARE
T-387	Entertainment Software Publishing (ESP)
T-388	NEC Home Electronics
T-389
T-390	Pulse Interactive
T-391	Random House
T-392
T-393
T-394	DigiToys/VIVARIUM
T-395	Mebius
T-396	Panther Software
T-397	Hitachi Media Force
T-398	NetVillage > Gamevillage/C's ware
T-399
T-400	Noisia
T-401	Shangri-La
T-402	Crave
T-403	Metro3D
T-404	Majesco
T-405	Take 2 Interactive
T-406	Hasbro Interactive
T-407	Rage Software
T-408	Marvelous Entertainment
T-409	Bottom Up > Softmax
T-410	Daikoku Denki/Falcon
T-411	Sunrise Interactive
T-412	Bimboosoft
T-413	UFO
T-414	Mattel
T-415	Caramelpot
T-416	Vatical
T-417	Ripcord
T-418	Sega Toys
T-419	Gathering of Developers
T-420
T-421	Rockstar
T-422	Winkysoft
T-423	Cyber Front
T-424	DaZZ/Nexus Interact
T-425
T-426
T-427
T-428	KOBI
T-429	Fujicom
T-430
T-431
T-432
T-433	Real Vision
T-434	Visit
T-435	Global A Entertainment
T-436
T-437
T-438	Studio Wonder Effect
T-439	Media Factory
T-440
T-441	Red
T-442
T-443	Agetec
T-444	Abel
T-445	Softmax
T-446	ISAO
T-447	Kool Kizz Amusement Works
T-448	GeneX/Ninelives
T-449	Xicat
T-450	Swing! Entertainment
T-451	Yuke's/THQ
T-452
T-453
T-454
T-455	TV Asahi
T-456	Crazy Games
T-457	Atmark/Yuki Enterprise
T-458	Hackberry
T-459
T-460	Jaleco
T-461	Starfish
T-462	Idea Factory
T-463	Broccoli
T-464
T-465	Princess Soft
T-466	Big Ben
T-467	G.rev
T-468
T-469	Symbio Planning
T-470
T-471	Alchemist
T-472	D3 Publisher
T-473	Playmore/SNK
T-474	D3 Publisher
T-475	"Chara, Rainsoftware/Milksoft"
T-476	GN Software (Good Navigate)
T-477	Alfa System
T-478	Milestone Inc.
T-479	Triangle Service