In 1975, St. Andre wrote rules for a fantasy role-playing game he called Tunnels & Trolls (T&T) as a rebellion against the recently published Dungeons & Dragons which he felt was heavily dependent on the use of miniatures, with which he had no experience.

He continues to write fiction and gaming materials published under the Trollhalla Press Unlimited[3] imprint, for items produced with his game design partner and artist Steve Crompton, and under the Trollgodfather Press imprint, for everything else St. Andre publishes.

In June 2018, The Academy of Adventure Gaming Arts & Design inducted St. Andre into its Hall of Fame.

[6]: 35 [7] He asked Rick Loomis of Flying Buffalo to sell 40 copies of Tunnels & Trolls at Origins in July 1975.

St. Andre has written many modules and stand alone adventures for Tunnels & Trolls, including the gamebooks Deathtrap Equalizer Dungeon and Naked Doom in 1977 after Loomis's own Buffalo Castle.

In 2015 Flying Buffalo released a Kickstarter-funded Deluxe Edition of T&T, authored by St. Andre, Steve Crompton, Elizabeth Danforth and James "Bear" Peters, known as "The Fellowship of the Troll".

with expanded rules along with an updated The Toughest Dungeon in the World adventure module, both published by Trollhalla Press Unlimited in 2020.

[13][14] In June 2018, The Academy of Adventure Gaming Arts & Design inducted St. Andre into its Hall of Fame.