Bought this on impulse at the weekend and think its pretty good, any similar games with a dark under-current theme like this one?

Try Dreamweb. Get it on the ScummVM website.

darkseed 1 + 2.

Phantasmagoria 1+2.

Hotline Miami

Postal 1.

Downfall.

Noctropolis, which I would like to see GOG bring back next in the FMV game line.

None of my suggestions is *exactly* like Harvester, some of them are pretty tame, in comparison (it's not hard to be pretty tame when compared to Harvester, mind you), but somehow either the themes, subject matter, aesthetics or simple gameplay nods all remind me a bit of Harvester. Here we go:

- Dark Seed and Dark Seed 2; (I think the first one is better than the second one. These are the closest to Harvester I can think of, you can get them in most abandonware sites);
- Sanitarium; (an incredible point and click adventure that even though lacking Harvester's crude approach more than makes up for in writing and disturbing psychological imagery -- some of the people that made Sanitarium worked on Dark Seed as well);
- Waxworks; (I have this one wishlisted on GOG ever since they released it but have yet to buy or play it, but from what I can see in screenshots and videos of the game, it sure as hell has some crazy vibe going on);
- Deadly Premonition; (OK, this one might seem a little off for me to recommend, but do note that both Deadly Premonition and Harvester have this over-the-top quirkiness to them, they both feature worlds that seem normal at first but turn out to be weird and dream-like, both strongly focus on the horror aspect and both are highly influenced by the best TV series ever, Twin Peaks);

These are the few that come to mind, if I think of more I'll add them. Hope it helped!

[edit] Adding

- The Dark Eye (not sure how you'll get this one, at least... legally, but it's a damn great game);
- The Residents' Bad Day on the Midway; (suffers from the same problem as The Dark Eye -- both were published by InScape --, so, good luck finding it. This one comes straight of the twisted minds of The Residents);

Hotline Miami owes a TON to this one. Almost forgot about it!

I second the recommendation of the Phantasmagoria games and Waxworks and recommend the Gabriel Knight series on top.

They all fit. I have No Mouth and Must Scream feels like this game. Deadly Revolution has the same twisted Twin Peaks give.

Good call. Have this one on CD myself, very much a fan of the band.

Bad Mojo is another deranged psychological horror game that is quite good.

Thanks for the cool suggestions...(er....Hotline Miami?)

I have Deadly Premonition and enjoyed it is quite quite similar in vibe. Sanitarium I also have and the GK stuff.

A lot of those listings are just what I was looking for, so reps to you all for the help :)