Descent 3: Mercenary (expansion pack) This had 7 mission, as opposed to 15 missions in the Descent 3 base game, but the missions/levels seemed considerably smaller and faster to finish, like half the size. Which was good because frankly many of the original Descent 3 maps were too large to my taste, they just kept going on and on and on...
The expansion pack didn't change my love/hate-relationship with Descent 3. Maybe the gameplay in the expansion pack was a bit easier (in Insane difficulty), but still there were times I hated playing the game, while other times I loved playing it.
Maybe the biggest highlight in Mercenary was the sixth mission, where you can "hack" the big bad enemy turrets to fight on your side, by blowing up that glowing "thing" which is somewhere near each turret. Damn it felt good rushing into middle of very hard enemies and such turret, then being able to destroy that control dome thingie, and speeding away knowing that that turret has just been converted to your side and started killing all the poor enemies around it. Bwahahahaha! That was a great mission.
But the ending boss... OMFG. Apart from maybe one boss in the base game (the spider-like thingie which doesn't fly and you have to shoot at its limbs), all Descent 3 bosses sucked. Same for the end-boss of Mercenary. A huge robot which WILL kill you about hundred times before you succeed in killing it. I had already caused considerable damage to it in Insane difficulty, but at some point said "phuck it" and changed the game to the easiest Trainee difficulty, just to be done with it. A very stupid boss fight.
Moreover, I had the same technical problem with the last Mercenary boss as I had with the base game end boss: the game kept crashing very often. It seems to be related to some visual effects or sounds when the boss shoots thousand things at the same time.
https://www.gog.com/forum/descent_series/descent_3_last_boss_keeps_crashing/page1 Anyway, after about 100 crashes and reloads, I finally made it to the end and could see the short end video.
Playing Descent 3 made me finally install Forsaken to try it out too, but I am unsure if I want to confinue playing it, it seems a bit too archaic after playing Descent 3. Flying in very narrow and small corridors...