AdamR: A generous GOGer surprised me with it recently. I've spent several hours playing it (campaign and skirmish modes,) and I think it is really fun. I thought It blended RTS and RPG pretty well.
In the campaign, you control a hero like you would in an RPG - you have an inventory, you level up, use skills, and trade at shops in the world. At the same time, you command an army in traditional RTS-style. Some missions include base building, some don't.
In skirmish/multiplayer mode, you choose at the start of the game whether you want to play as a hero and recruit "neutral" units - or you can choose to trade your hero for a base and build your own army. You can play as 4 different races, and they are all very unique with diverse units and spells.

I'm not very good at it, but I've had a ton of fun playing it.

IAmSinistar: Should be pretty cheap if you already have parts of it. But then, do you want the parts you don't have?

Grargar: Do it. Otherwise, I'll utter a terrible pun.

HypersomniacLive: I'm missing only two titles, Real Myst and Myst 5: End of Ages Limited Edition, and my dilemma is exactly that - do I want them?
Do I go for it today, or wait to see what the next days bring, and decide on the encore day? Of course it'd be ironically hilarious (or hilariously ironic?), if GOG doesn't do an encore day at the end.

HypersomniacLive: I dare you, perhaps it'll help me make up my mind.

HypersomniacLive: I'm missing only two titles, Real Myst and Myst 5: End of Ages Limited Edition, and my dilemma is exactly that - do I want them?
Do I go for it today, or wait to see what the next days bring, and decide on the encore day? Of course it'd be ironically hilarious (or hilariously ironic?), if GOG doesn't do an encore day at the end.

Grargar: Since a bit more than half an hour has remained before the end of its flash sale, can you tell me if it's fast-paced or not? I prefer a RTS that doesn't have missions that last hours and hours.

IAmSinistar: I think you're safe waiting for the reprisal, seeing as they've done one already. I doubt they want to alienate customers by not doing another.

AdamR: I've only played I think 6 missions from the campaign. I didn't pay that much attention to the time, so I'm just estimating here... One of them took about an hour, maybe a little more. The rest were all 15-30 minutes.
My skirmishes seem to be around an hour.

Grargar: Don't tell me I didn't warn you. You will be a fool to have myst this opportunity!

HypersomniacLive: At least you didn't say this bundle is Mist! ;-)

Grargar: Then Building/Unit creation didn't take too much time, right?

AdamR: It depends on the race, I think. Each race requires different types and amounts of resources to build stuff.

I've found that building a base seems to take a while, but training units is really fast. You can construct multiple buildings to train units, so you can have hundreds of soldiers in minutes.

HypersomniacLive: At least you didn't say this bundle is Mist! ;-)