Hi, I'm new to this platform and bought Heroes 3 today as it was one of my most beloved games in 1999. And I would really appreciate it if someone can suggest me games available on here that are of that era late 90s early 2000s as I've big nostalgia towards them. Thanks

https://www.gog.com/game/cossacks_anthology
https://www.gog.com/game/stronghold
https://www.gog.com/game/startopia

Curse of Monkey Island
Grim Fandango
Desperados
Commandos series
Morrowind
Hitman series
Quake series
Unreal series
X-Wing series
Broken Sword
Splinter Cell
Toonstruck

I've opened a GoG account just to buy Port Royale 1 and Gangster: Organized Crime. I highly suggest to try them. Beware though: for some work, for some they doesn't. Gangster in particular, it can be a pain in the ass to make it work.

Other older games I suggest:
- Age of Wonders Shadow Magic (on sale right now)
- Tropico Reloaded
- older Paradox games, all of them (your eyes will bleed A LOT)
- Patrician 3
- Unreal Tournament 99 (Unreal bots are really unreal, they are so good)

Go to games, sort by oldest first. Find your earliest game and then look from there. Without knowing specifics of what you enjoy it’s hard to say, but some big titles are:
Diablo
Baldurs gate
Never winter nights
Warcraft
Elder scrolls
...

thanks a lot for the suggestions! I remember some of these series and will have a look at them

Dungeon keeper is still a fun game to play.
Mortal Kombat 1+2+3 are DosBox games but the difficulty is way higher than console ports. (I dont remember being so bad when playing on megadrive)
X-com games are available too.
Populous games (Populous 3 is one of my all time favorite game)
Wolfeinstein

and of course Theme Park an Theme Hospital :D

If you love HOMAM, you should check out Might and Magic too (6-8), HOMAM is actually a spin-off. MM series is an RPG, and storywise MM6 takes place after/concurrently with HOMAM II, MM7 around or after HOMAM III and MM 8 takes place before HOMAM IV.

The first five MM games take place in a different world(s), so you don't need to play those, however they're fun as well. They are turn-based, while 6-8 can be realtime or turn-based, so they're interesting to try out and the first six games actually come as one game (a six-pack).

Enclosed is list of my favorite games of that era, I can recommend all of them!

Icewind Dale 2
Temple of Elemental Evil (bit later, but why not)
With NWN EE you can get NWN Diamond....

Clash just came to gog.
Worms series
Jagged Alliance series
Robin Hood: The Legend of Sherwood