Ostensibly a space trading and combat game, but one with insane amounts of detail. Sundog is a game that's been bizarrely lost to the collective memory, but is every bit as classic as the finest entries in the genre.
The 'Zoomaction' system was a brilliant way of presenting the potentially complex facets of the game to the player. You never had to use anything other than the mouse. Clicking the mouse buttons took you down or up levels in the menus, and literally inside whatever vehicle or building you were in. You could walk around your ship for example and personally check on the engines or shields while in flight or even combat (racing to replace damaged shield batteries and engine parts during combat was hair-raising stuff).
There's also a pretty large RPG element. Your stats are determined at the start of the game by spending from a pool of points. Strength, Intelligence, Charisma etc. will affect your abilities in various areas in the game. You could be attacked on the street while walking to the bank, or have to persuade a character to give up some vital information. Yes, in this game you can not only land on planets, you can get out of your ship and into a car, and out of that and walk around. Be careful where you park though, or you may get a ticket! You even had to feed yourself and make sure you got enough sleep.
There is a strong storyline that develops during the course of the game, and following it will lead to an end screen (which is unusual in itself for such an open-ended genre). I never saw it though, because I always enjoyed bashing around the galaxy too much.