Oldgamer commented:
Versions and single player mode:
Without the proprietary server, multiplayer cannot be played anymore. Single player campaigns were added very late.
Latest version was v3-10 in 2006 (https://web.archive.org/web/20100529023253/http://www.lasersquadnemesis.com/News.htm) downloadable only after login
- version 3.09 (retail release), includes 4 single player campaigns with 5 missions each; game asks for the CD to be inserted which contains dummy sectors (works with image) ;
- version 2.14, with single player tutorial missions, no single player campaign ;
- version 2.12, it's a full installation of an older version ;
- several other versions are now available on this page ;
- Actually the game is not bigger than 15-20MB uncompressed; The CDs only contain DirectX additionally
If the campaign is too hard on Rookie:
You can edit the unit properties in file Configs\Laser Squad Data.cfg
English 
Polish 
Comments and reviews
You will need this: https://github.com/solodkiy/lsnd
To be able to play; but it requires somewhat of a networking and python knowledge.
Cool game, works on Windows 10 with no problem. Multiplayer servers are dead but you can use hotseat and software called Parsec to do multiplayer. I reading also reading on reddit that someone written a server emulation software but at that time it was very hard to set up and appeared complected to use, it was probably about 5 years ago when I heard about that.
There is an X-Com like Game Boy Advanced game from the same developer, which can be played in an emulator: "Rebelstar: Tactical Command" (2005)
Install Alt ISO Version for free version
Runs great but I can't figure out how to get the single player missions to unlock or be available.
Yeah, it was originally only available to play online against another person by paying a monthly subscription fee; great concept (play against other via email turn-by-turn), but the subscription fee killed it before it could get any traction. Such a waste!
Wasn't this an online game only where you had to send your save file to an online server?
No comment nor review for this game at the moment.