I bought Cossacks + add-ons on CD years ago and loved it. On that basis I bought Cossacks 2 but I never really got into it; I definately prefer Cossacks 1.
However, over the years the PC's were replaced, and newer versions of Windows were used, and I was no longer able to install and play the game (on CD), so when I came across GOG selling it as a complete bundle for a few ££ I was instantly attracted to it, but I was concerned it still might not work on my even newer machines using Win 7 and Win 8.1. I read various peoples comments and I got the impression that it 'should' be ok. As there is no real risk to purchasing from GOG I went ahead and bought it and I can confirm that it works great on 2 of my 3 Win 7 Laptops.
1. HP Pavillion DV8000 (about 7 yo) - Win 7, Dual Core, 2gb Ram, 128mb Radeon Xpress 200m Gfx - Works great (Suffered Graphics corruption with CD version)
2. HP 4730s (3 years old) - Win 7, i7, 4gb Ram, 1gb AMD 6490m Gfx - Black Screen, hasn't crashed, but won't display properly - I reckon I can get it going with a little more effort.
3. Samsung (1 yo) - Win 7, i7, 8Gb Ram, 2gb AMD Gfx - Works great,
The game itself - Excellent use all the various features that you expect of RTSs. Research tree, Multiple Building Types/Upgrades, Unit Types/upgrades (Infantry/Horse/Cannon/Ships etc). Peasants for buidling and Resource collection. Terrain/Fog of War/LOS all affect battle.
Multiple mixed types of soldier can be grouped, but they won't be proper formations. However, proper units/formations are created using a Leader & Drummer and an even number of one type of men. e.g. 72 Pikemen and the other 2 together. Click on the leader to form them into a proper unit; Much more effective.
Games can be quick skirmishes, or long epic battles with massive armies. See the photo's.
You'll loose the first few games quickly, but you'll get the hang of it. One trick is to keep a few men dotted around the map as spotters.
Anyway, it comes highly recommended by me :)