Greg has often taken the role of "bitter veteran" in the video game industry, decrying the stifling model of mainstream publishing and being one of the early advocates of the Indie Game scene. In September 2005, he joined with Johnny Wilson, former editor of Computer Gaming World, to create the startup indie game publisher Manifesto Games. As a digital distribution hub it was ahead of its time but it would be eclipsed by institutions such as Steam and the Humble Bundle, and the site eventually went out of business. Manifesto was for a time survived by the blog Play This Thing!, an indie Review Blog (with regular tabletop features on the side), but this seems to have gone down as well after a time.
Costikyan is also known for his 1994 essay "I Have No Words and I Must Design", which was one of the first attempts to develop a unified language for game designers to talk about their discipline — and he did it years before academic game studies even became a thing. In 2013, he published his first game design book, titled Uncertainty in Games, which explores the role and implementations of Unpredictable Results in gaming experience.
He also writes on a variety of topics; his non-fiction writing tends to focus on game design and the role of games in culture, and he has written a few science-fiction novels as well.
Costikyan's works include:
- The Creature That Ate Sheboygan
- Star Wars: The Roleplaying Game, specifically, the first iteration, a.k.a. Star Wars d6
- Pax Britannica
- Toon: The Cartoon Role-Playing Game, co-developed with Warren Spector
- Violence™: The Roleplaying Game of Egregious and Repulsive Bloodshed
- Web And Starship
- Vector 3
- Another Day, Another Dungeon
- By The Sword
- First Contract
- One Quest, Hold the Dragons
Other works by Greg Costikyan contain examples of:
- Crazy-Prepared: Spoofed in Another Day, Another Dungeon. In the Dungeons and Dragons rule book, the list of standard equipment items included a ten-foot pole, which generated much player lore about the uses for this item and about GMs responding by putting useful items eleven feet away to keep them out of reach. For this reason, one of the main characters in Another Day, Another Dungeon carries a collapsible eleven-foot pole.
- King Incognito: In Another Day, Another Dungeon, Vic, the senile old man who tells long, pointless stories and begs for spare change, turns out to be the last polymage, a type of sorcerer thought to have died out more than ten thousand years ago.
- Our Liches Are Different: In Another Day, Another Dungeon, a lich functions as the main Big Bad's dragon. He's an undead sorcerer, but he's pretty much the Only Sane Man for Team Evil. He once spent a century as a disembodied skull being used as a birdfeeder, and it's left him with an almost uncontrollable urge to kill all songbirds.
- Prince Charmless: In By the Sword, the princess has great misgivings about her Arranged Marriage to one of these princes. The prince is fat, smelly, and has bad table manners. The princess eventually talks to a member of the prince's court, who explains that the prince is actually a very gentle man, and he's also extremely gay, so the princess never has to worry about having to have sex with him. She is reassured by this, and decides that this marriage won't be so bad.
- Shout-Out: Costikyan's the title of famous essay "I Have No Words & I Must Design" is a play on Harlan Ellison's short story I Have No Mouth, and I Must Scream.
- True Love's Kiss: Deconstructed in the short story "And Still She Sleeps". No one can wake up the maiden who's been asleep for centuries, because no one can truly love her when they can't get to know her. In the end, they put her in a museum until some future wizard can figure out how to wake her.