MartiusR: A bit tough topic, but I'll try:
1.Laser Squad: Nemesis / UFO: Gniew Boga (sadly, not available in digital distribution, but used copies on various auction portals have rather reasonable prices) - tactic game, sci-fi theme, 4 playable races, you're making orders in turns, then watching "results" for short time (similar solution was also used in Combat Mission), it's almost 100% tactic, as the "bases" (which you can set before battle) are used just as a hubs for replenishing ammo.
2.Missionforce: Cyberstorm - definitely focused on tactic combat (turn-based of course), economy is minimal, present only between missions. One thing - there are fighting only robots/mechs, so IMO it's the thing which will make a difference comparing to Starcraft.It's available on GOG.
3.Already mentioned Warhammer 40k: Sanctus Reach - IMO it's one of the most accessible turn-based tactic games, so it definitelly shares with Starcraft the "accessibility" feature, aside from that, it's WH40k universe, so I guess that part is rather self-explanatory (important thing - in base game you have available only Space Marines and Orks, two DLCs are necessary to have 2 additional races (Imperial Guard and Chaos Demons).It's also present on the GOG.
4.Fallen Haven & Fallen Haven: Liberation Day - rather accessible game, economy is happening "between missions", it's definitely on bigger scale than previously mentioned games (maybe comparable iwth Sanctus Reach) in terms of amount of units present on the battlefield. Of course present on GOG.
5,Already mentioned Battle Isle: Incubation - extremely accessible, extremely fun, has very challenging campaign though.
Fallen Haven comparable with Sanctus Reach? That is a bit stretching it, no? Sanctus Reach is this skirmish based turn baser where you guide your set number of troops through a variety of missions that all look similar while Fallen Haven is this expand/exterminate game where you build up both forces and defenses while trying to capture sectors and gain the upper hand before your single opponent does that on you. Its amazing how that game's graphics managed to survive the test of time btw!