The only connection between Irem and 3D Dot Game Heroes is the appearance of Spelunker in game and in advertisements; he is also rumored to be a playable character. They're not the developers.

While the zelda game feels like a complete and utter remake of ALTTP, I can't really see the connection with Metroid and the first game you showed. The only real similarity I found was the map. I've just been spending the last 4 weeks playing through all the Metroid games as well...

Can you explain your point a bit more? I'd like to hear your reasoning if it delves deeper than what you said in your first post. Maybe some more specific examples of what you mean that I missed.

Well, I don't think Shadow Complex is exactly like Metroid. Sure its an Action/Shooter title on a 2D plane, but if that makes it the same as Metroid, then you could easily say Smash Bros Brawl is the same as Metroid. Or a ton of games on the NES and SNES. I'd say its more of a game with a similar game engine, but unique gameplay in all other ways.

Also, I can't tell what the heck is going on with that 3D Dot game at all! But it definitely looks interesting still.

For those who don't think Shadow Complex is like Metroid:

While there is more combat, Shadow Complex is a 2D Open world action adventure game. You explore the world via hidden doors, passageways, and vents, more of which become available as you aquire new gadgetes. The world is divided up into distinctive locations (like the factory, lake, armory, etc.). Included in Shadow Complex are the ice beam (foam gun), grapple beam (hookshot), wall jump (climbing gear), missiles (missiles), even the freaking power suit, and then a couple of its own gadgets.

Skill with platforming is essential to completing the game, and exploration and creative use of the gadgets is necessary to collect all items and upgrades. Trust me, I'm a longtime Metroid fan, and I've played every Metroid game many times. Shadow Complex is Metroid. The main gun may not be the same, and there may be a bit more combat, but it's Metroid. Not Contra, Metroid. The reason there is nothing but action in that trailer is that they were trying to market the game to shooter fans, who wouldn't want to see someone jumping around in hidden passages. They want to see stuff blow up.

If you don't believe me, here's an excerpt from the 1UP review:

"To call Shadow Complex inspired by the Metroid series would be a terrible slander to the word "inspiration." It's not so much that the developer, Chair, looked to Super Metroid for ideas as it is that they took a sheet of wax paper and did a rubbing of Samus Aran's entire career. It's a clone."

wow, this is the first time I watched a video of 3D Dot Game Heroes and now I'm wondering how Nintendo hasn't sued them to stop the game. If I didn't know any better I would think I was watching Zelda with weird 3D cube graphics.

It's a blatant Zelda clone and looks awesome for it. Actually of the 3 that's the game I want the most (well, I already have Shadow Complex).