The X series of games (
X: Beyond the Frontier,
X-Tension,
X2: The Threat,
X3: Reunion, and
X3: Terran Conflict) are all great sandbox-style space games. The first two are of the "very old" variety that can be rather complex to get a hold of, X2 is a median, and the X3 games are beautiful with both merchant and combat aspects. All of them have their plotlines, but the games mostly revolve around building your fleet and/or empire. Micromanagers rejoice, though it isn't necessarily required.
As a note, the X3 games lost a lot of features (mainly graphical) of the earlier games, such as the "exhaust" trails. Fortunately, there's a
Scripts & Modding Forum (That's the X3TC one. There's one for X3R and X2 as well.) chocked full of all sorts of add-ons. If you play without any sort of modification, you can upload your game statistics to their server. You losethat ability with mods...but, in my opinion, they really make the game shine.
