A combination of Historical, Sword and Sorcery, his Bard series (5 books) is an enjoyable take on the bard of history and the bard of more popular fancy. I don't know if he is a gamer, but the series is wonderful inspiration for gamers. I can recommend the first three books in the series. I stopped reading somewhere shortly after starting book 4 (and can't remember why) and only recently picked up book 5.
He has a long list of short stories but the work is a bit too recent for me (I've never read any of the newer Weird Tales magazines or caught the work he did in the 70's).
Series
Bard Bard II The First Long Ship Bard III The Wild Sea Bard IV Ravens' Gathering Bard V Felimid's Homecoming
The Sorcerer's Sacred Isle The Cauldron of Plenty Search for the Starblade
Novel
Lances of Nengesdul The Tower of Death (with Andrew J. Offutt) When Death Birds Fly (with Andrew J. Offutt)
Short Story
"A Spear in the Night" "The Archpriest's Potion" "The Atheling's Wife" (as Dennis More) "At the Edge of the Sea" "The Bath-house" "The Brotherhood of Britain" "Buried Silver" (as Dennis More) "The Castles of Testing" "The Company of the Gods" "The Conqueror of Vectis" "Corpse's Wrath" "Daggers and a Serpent" "The Demon Cat" "Dragon Hunter" "The Emerald Scarab" "Emissaries of Doom" "The Favour of a Tyrant" "The Forest of Andred" (as Dennis More) "Fugitives in Winter" (as Dennis More) "The Harvest of Malice" "Haunted Shadows" "The Haunting of Mara" "Hungry Grass" "The Lady and the Demon" (with Paul Collins) "Lamia" "The Lost Ship" "Men from the Plain of Lir" "On Skellig Michael" (as Dennis More) "The Ordeal Stone" "Revenant" "The Scribe of a Hundred Lies" "Sir Lionel in Tournament of Rogues" "Spears of the Sea-Wolves" "Spirit Places" "Sunchosen" (as Cadmus Evans) "Tournament of Rogues" "The Unlawful Hunter" "The Walking Walls of Rome" "What Are You When the Moon Shall Rise?" "Where Silence Rules" "The White Doe"
Read the first book in the early 80's, and I enjoyed it. Can't remember it at all, though.
It was not my favorite but I thought it was good to very good. I do feel that it did a great job portraying a version of a bard that could be used in gaming and that it integrated magic very well into historical fantasy.