|Type of business||Joint venture|
|Headquarters||Redwood City, California, United States|
|Industry||video game industry|
|Products||video game publishing|
SegaSoft, originally headquartered in Redwood City, California and later San Francisco, was a joint venture by Sega and CSK (Sega's majority stockholder at the time), created in 1995 to develop and publish games for the PC and Sega Saturn, primarily in the North American market.
In 1996, SegaSoft announced that they would be publishing games for all viable platforms, not just Saturn and PC. This, however, never came to fruition and SegaSoft mainly focused on the PC.
SegaSoft disbanded in 2000 and many of the staff members were merged into Sega.com, a new company established to handle Sega's online presence in the United States.
SegaSoft was responsible for, among other things, the Heat.net multiplayer game system and publishing the last few titles made by Rocket Science Games.
- Alien Race
- Bug Too!
- Cosmopolitan Virtual Makeover 
- Cosmopolitan Virtual Makeover 2
- Da Bomb
- Emperor of the Fading Suns
- Essence Virtual Makeover
- Fatal Abyss
- Flesh Feast
- Golf: The Ultimate Collection
- Lose Your Marbles
- Net Fighter
- Plane Crazy
- Puzzle Castle
- Rocket Jockey
- Scud: The Disposable Assassin
- Scud: Industrial Evolution
- The Space Bar
- Three Dirty Dwarves
- Trampoline-Fractured Fairy Tales: A Frog Prince
Heat.net, stylized HEAT.NET, was an online PC gaming system produced by SegaSoft. Heat.net hosted both Sega-published first- and second-party games, as well as popular third-party games of the era, such as Quake II and Baldur's Gate. Each supported game had its own chat lobby and game creation options. In addition, players could add friends and chat privately with them.
Heat.net was based on a licensed version of the MPlayer Internet multiplayer gaming system which was later bought by GameSpy. It branded itself as a peaceful alternative to real-world violence with advertising slogans such as "Total peace through cyberviolence" and "Kill pixels not people."
It featured a currency system where the player earned "degrees" through playing games, trivia contests (both game-related and general), viewing ads, or other actions. Degrees could be spent, but only by premium members, at Heat.net's online store, the Black Market, which had computer games and related merchandise. On May 6, 1999, SEGA announced it had partnered with Chips & Bits' online game superstore which allowed players a vast selection of games, hardware and even magazine subscriptions.
The degree system was highly flawed and non-active players could leave their PCs logged into servers and earn degrees. Rooms were established for idle players to sit and earn degrees. Heat.net established "parking police" to discover these servers but players discovered other ways to falsely earn points.
Heat.net had a loyalty program, in which members, known as "Foot Soldiers", received shirts and Heat.net dog tags.
Heat.net was also the home a collegiate gaming league called HeatCIGL (College Internet Game League). Students from 1,100 registered schools would play Quake II or Unreal Tournament in teams representing their colleges, with play-offs at the end of the season. The championship team received $5,000. The league also gave away a $5,000 "Excellence in Gaming" College Scholarship. 
In September 2000, it was announced that Heat.net and HeatCIGL would be shutting down on October 31, 2000.
In June 2008, CNET hailed Heat.net as one of the greatest defunct websites in history.
Partial list of games supported on Heat.Net
- Sega-published titles
- Third-Party Titles
- Age of Empires II 
- Age of Wonders
- Army Men
- Army Men II
- Baldur's Gate
- Duke Nukem 3D
- Get Medieval
- Grand Theft Auto
- Heroes of Might and Magic III
- Hexen II
- Kingpin: Life of Crime
- MechWarrior 2: 31st Century Combat
- Quake II
- Railroad Tycoon II
- Red Alert
- Requiem: Avenging Angel
- Star Trek: Starfleet Academy
- Take No Prisoners
- Total Annihilation
- Unreal Tournament
- Uprising 2: Lead and Destroy
- Warbreeds 
- Warcraft II: Tides of Darkness
- Warlords III: Reign of Heroes
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- "HEAT.NET Celebrates First Anniversary With 12-Hour Online Bash". SegaSoft. Archived from the original on 11 December 2000. Retrieved 29 December 2017.
- "Teen Gamers Can Now Purchase Online Without Credit Cards: HEAT.NET Frequent Player Points are as Good as Cash at Partner sites". SegaSoft. Archived from the original on 11 December 2000. Retrieved 29 December 2017.
- "GAME YOUR WAY THROUGH COLLEGE! HEATCIGL KICKS OFF SCHOOL YEAR WITH MORE CASH, CONTENT AND PRIZES THAN EVER BEFORE". SegaSoft. Archived from the original on 7 December 2000. Retrieved 29 December 2017.
- "The greatest defunct Web sites and dotcom disasters". CNET. 2008-06-05. Archived from the original on 2008-06-07. Retrieved 2008-06-05.
- "10six". 10six. Archived from the original on February 25, 1999. Retrieved 16 March 2016.
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- "ANGELIC POWERS BATTLE HELL'S DEMONS ON HEAT.NET". SegaSoft. Archived from the original on 11 December 2000. Retrieved 29 December 2017.
- "HEAT.NET Strengthens Relationship With 3DO - Features Four Highly-Anticipated Games For 1999". SegaSoft. Archived from the original on 11 December 2000. Retrieved 29 December 2017.
- "SegaSoftTM Brings Seven Red-Hot New Titles to HEATTM". SegaSoft. Archived from the original on 11 December 2000. Retrieved 29 December 2017.