Just a warning to all new players, game must be run in 800x600 otherwise a bunch of technologies are missing from the tech tree (due to scaling issues)

Eh you sure about this?
I played it at 1024 by 768 and had no problems.

Yeah, this is fixed in the expansion though.

just the expansion, if you play the legions of iron campaign you will be missing tech. The higher your resolution, the more tech will be missing.

as far as 1024 x 768 goes... did you steal all unique racial tech from the kharak and darzok?
Also, there is no reason to not play at max resolution until your tech tree starts filling up. And you can also start a mission at low res, research what you want, then switch to higher resolution

it should be noted that if you switch from high res to low res the lines for missing tech will be blank, but clickable... so you could still research, you just have to click on empty lines beyond the last one shown until you get the right tech.

Oh dear... is there any chance of GOG fixing this bug?

I also haven't noticed any problems playing at 1024x768 except that any heroes or units I don't take with me into the next mission vanish forever... but that doesn't seem related.

that is intentional

Is it really? It seems pretty buglike, especially for the heroes. In level 5 I think it is you get that one guy, and then captain McCain joins you, so you have two heroes. In level six you can only bring one. Then in level seven you get to bring two, but of course since you could only bring one hero on level six and any you don't bring vanish forever you only have one hero to bring! ... It would be pretty stupid if that was how it was intended to work.

Then again this whole game feels fairly unfinished, like they spend all their time on making those awesome explosions and then were like... "Fix the interface? Um... But splosions!"

Don't get me wrong, it's a great game. It's just kind of troikaish I guess.

Actually that is a balance decision...
the "core" heroes are always there and not shown in the "bring with" screen.
only randomly generated heroes (And a few scripted ones) which are not part of the plot and serve only to give you random bonuses are shown and selected. The idea is that you choose who to bring because in some of the later missions you will be getting a dozen heroes through the mission (there is also a cap on how many you can have at once).
Likewise with your fleet, you choose which ships carry over instead of taking your whole fleet with you. It is a balance issue to make sure new missions aren't too easy (if you brought a full fleet + very good heroes) or too hard (if you lost most your ships in the final push and you only hired weak heroes.

I agree with the techs not showing up, i was playing at 1600x1200 and the cruiser tech was not showing up, same with the spyship tech.

Its a old game issue with its poor designed interface with modern monitors.

I am unable to change the resolution to 800x600.
When I do the screen goes black and I have to use the taskmanager to close the program down.
Any suggestions?

Can anyone take a screenshot of this.

This is a text-scaling problem specific to GOG's version of Haegemonia, where a blank line is added between each line of text at resolutions above 800x600 (visible in the list of saved games also).

If you replace the hgm.exe file (back it up first, just in case) with the 1.07 no-cd version (later versions just patch the file, so quite likely won't work with GOG's version) from GameCopyWorld's Haegemonia page then this problem should go away.

If this is true then this is serious.
It means this is a bug introduced BY GOG.