I've heard about Warhammer like billion times, but never really played any. I haven't played any turn based games for that matter (Worms kinda don't count). But after watching trailer for Mechanicus, it got me super excited. I do like the RPG elements of fitting the player with gadgets, armor and weapons, but I kinda prefer real-time over turn based.

Would Mechanicus be a good place to start with Warhammer series and if I find it fun, go with older ones afterwards?

Well I haven't played Mechanicus, thanks to the Linux version being absent, but for the rest of your questions: there's no good place to start the Warhammer series. There is no series. Warhammer is sort of like Dungeons and Dragons: it's a setting and some rules. Different people have made many different series within this setting, in many different mediums, and this is one of those.

So even if you play and enjoy this game it doesn't necessarily mean that you'll enjoy previous games done by different developers. They don't have so much in common. That said, you may find that you really enjoy the setting and want to find some other good games and series within this setting. They exist, so that's great.

I don't know what would be a good starting place for turn-based games, I find that question hard to wrap my head around. I think in this case you may just have to jump in and see. Do try to give it a little time though, it's a different experience and it may take you a little while to come to appreciate why people like it.

Thanks. I guess I'll give it a try since it's not that expensive. I've asked similar thing on Reddit and ppl recommended Space Marine and Dawn of War. I'll check those out too. Yeah, I've noticed Warhammer has a central lore, but there have been bunch of developers and different games that don't necessarily connect to each other, other than through lore itself.

Space Marine is the closest one you listed to what you describe as your taste in games. Followed by specifically Dawn of War 3. DoW 1 is a pure RTS and DoW 2 is smaller scale RTS, squad level.

Personally, if you like FPS types or real time, WH40k May not be the best starting place. Many of the real time games havent been well received. The best of the license usually are turn based (both my personal opinion and general review consensus, though I am sure others feel differently). They have just released ChaosBane which is a Warhammer Fantasy license ARPG (Diablo 3 clone from what I read). That might be a bit closer to what you are looking for. Though initial reviews on that have been mixed as well, no idea why, havent looked into it myself.

EDIT: Sorry, specific to your question... Based on what you like... No, I wouldnt start with Mechanicus. Game play is exactly what it says, squad level turn based. Which didnt seem like your cup of tea. And the story/lore assume you know a lot about the universe already. There is zero introduction story-wise. Not that its a horrible thing, just that you will have no idea why a bunch of freaky cyborgs are exploring a tomb of terminators and they take no effort to explain it other than a few lines of intro text.

I have a bit over 11 hours in Mechanicus right now and at around 40% progress of the awakening and I love this game. I never thought turn based games could ever be this fun, but it is. It's also interesting how repetitive game actually is if you think about it, but since every scenario requires so different approach it just doesn't feel like it. Which is pretty neat. I now have 4x Tech-Priests already and Sikharii Vanguards are so badass with long range and ability to use weapon 2x. Have also slayed the tutorial boss, god damn necros cockroach.

Maybe I don't know the story on the grand scheme, but I've learned a lot about Necros and how hard we want to purge them with fire :)

Colloquilisms of Metalica, Chapter 52: "Enough fire in the right place can solve any problem."

Hehe :)