Dungeon Master

FTL's Dungeon Master was their breakout game, and indeed a groundbreaking title in quite a lot of ways.  Rather than being turn-based as many other first person dungeon crawlers of the era were, it operated in real time - roughly every second constituted a round, and any actions enemies and allies took were followed by a cooldown where they could take no further actions before the next round began.  Casting spells was handled not by typing in words or simply picking from a list, but by selecting a sequence of runes to create various effects; for example, clicking the rune for "Fire" would create light temporarily, while clicking the runes for Fire and Flight would create a fireball to strike the enemy in front of you.  Not just any combination works, though, so finding spell recipes on scrolls strewn throughout the dungeon is vital to discovering which ones will.  Taking other cues for realism, one must also have a light source to see in the dungeon, either via spells or lit torches (the latter of which gradually fade over time instead of abruptly cutting out), and the party has to eat and drink to sustain themselves.  One can also toss rocks, shurikens, et cetera at enemies or distant switches and pick them up again later for reuse; something pretty novel compared to most other games, where arrows and thrown weapons were one-use items.  The game is also among the first to exhume the traditional "experience level" system seen in so many other D&D inspired computer titles - instead, your skills are gradually improved through use, so fighting enemies at short range will make you better as a Fighter, ranged weapons (or bare hands) make you a stronger Ninja, and casting spells and brewing potions will gradually make you a stronger Priest or Mage.  Not only an amazing game for the period it was released, but a major inspiration for games like Eye of the Beholder and Ultima Underworld, the latter of which would become an incredibly influential title in its own right.

(Despite the similar name, it also has nothing to do with the 1985 film "The Dungeonmaster".)

Developer: FTL Games, Victor Musical Industries
Publisher: FTL Games, Victor Musical Industries
Platform: Atari ST, Apple IIGS, Amiga, MS-DOS, SNES, TurboGrafx-CD, X68000, PC-9801, FM Towns
Released: 1987, 1988, 1990

Sundog: Frozen Legacy

A game that I'd never heard of until recently, though after reading an interview in which Richard Garriott named it his favorite game of all time and seeing it listed as an inspiration for Bethesda's upcoming Starfield, I decided to give it a go.  After playing it I can certainly see why two major names in gaming cited it as such a big influence, as it's got quite a lot going on for a 1984 release.  Built on a similar premise to Elite (released the same year), you start with only a beat-up spaceship and a pocketful of cash, and set out to fulfill your late uncle's final contract.  To that end, you must buy and sell commodities to make money, gradually fix up your ship and its many broken parts, and seek out a number of would-be colonists in cryogenic stasis on numerous planets in order to help them form a new colony for their religious order.  Of course, it's never as simple as it sounds - in addition to fluctuating market prices, you constantly deal with ne'er-do-wells from street muggers to space pirates who want to rob or outright kill you.  Sometimes you can bluff your way out of a fight, but more often than not you'll have to resort to good old gunplay to neutralize the threat.  And of course, you have to manage your own health and replace or repair broken parts to keep your ship running, or your mission is all for naught.  Sundog has a surprisingly simple interface in spite of its complexities, using only a two-button joystick or mouse; in fact, it's one of the first games I'm aware of to be entirely mouse/joystick driven with no option to use the keyboard, so it's relatively easy to pick up and play, especially for an '80s computer game.  An influential and very ambitious game with some elements that haven't been replicated in any other game to date, but it also falls prey to hardware limitations of the era - the overall gameplay is very slow-paced and repetitious, and the end goal boils down to little more than a very long game of tedious searching, clue chasing and trial-and-error.  Two more sequels were also planned to expand on the game's story and universe, though owing to Bruce Webster's departure from FTL and the runaway success they experienced only a couple years later with Dungeon Master, they ultimately never materialized.  A game worth a look as a historical curio for serious RPG fans, though fans of these type of in-depth market and spaceship sims have plenty of more sophisticated modern alternatives these days.

Developer: FTL Games
Publisher: FTL Games, Accolade
Platform: Apple II, Atari ST
Released: 1984, 1985