There are plenty of console-like products on the market, that fully support Unity, and generally follow the development process of a modern Android device.

The Ouya, while dated, can be bought for cheap. NVidia's Shield TV is a very capable modern alternative, albeit a bit pricy. Razer's Forge, Amazon's FireTV... the list goes on.

If you want to go even older you can try out older Home Computer systems, like the C64 or Atari. They are quite simple (albeit not without quirks), emulators are available and the systems are usually documented out the wazoo.

Endurion, could you please give me info an Atari-like system? An Atari-like system sounds perfect. Look at this title screen screenshots from "Force Disruptor". It's an Atari imitation. The code is lost, but I still have some screenshots. I'd like to program it again.

Do you think I could purchase an old Atari plus empty cartridges and a writer to write games? If the answer is "YES!", then please send me some links.

Been currently working on getting my game running on the Switch and its been awesome so far. Great documentation, awesome GPU, awesome CPU (ARM based), been so much fun to program for. 

If you just want to do something that's needlessly hard and requires obsolete kinds of low-level fiddling, then you could just make DOS games  You can run a DOS emulator on any PC. 

To make it feel like a console, you could buy a tiny linux computer the size of a gameboy cartridge and put it inside a box with a screen. Then you get to do a fun DIY electronics project too!

Dreamcast and IIRC PS1 (or was it PS2) had homebrew communities at one point.  I haven't checked them out for a long time though.  You could also try a raspberrypi, although I don't know if the video acceleration hardware is open or not (I think its a closed source blob).  GBA or DS homebrew might be the way to go, but as hodgman said old DOS PC is a pretty good choice as well.

13 hours ago, Brian.Washechek said:

Do you think I could purchase an old Atari plus empty cartridges and a writer to write games?

I think that about the same way I think that if you buy a piano you could play songs by Chopin, Mozart, and Beethoven.

Yes, with the right tools and sufficient experience and training and effort people can create the games.  Someone with sufficient training and experience can use an instrument to play concert pieces. Someone with the right background and the right sporting gear can play sports at professional or pro-am levels.

Few people choose to do it, but it is certainly possible.

You could buy all the tools, that is the easy part.  You then need to learn how to program, learn how to design and build games, learn how to develop on the assembly language the computer used, learn the exact timings of the cpu instructions because that was how they coordinated what appeared on the screen.

Most of the programmers on those early systems were mathematicians (often with bachelors or masters degrees in mathematics) who could take many mathematical shortcuts because they understood the math at a deep and fundamental level, finding ways to implement the algorithms that exactly equaled the time requirements, making tradeoffs between math results to fit the timings perfectly.

That doesn't mean you could not do it, many people invest the time and effort to do it. Just like many people invest the time and effort to learn to play the piano to master levels.  But understand that you're talking about a long journey before you reach the destination you're discussing.

13 hours ago, Brian.Washechek said:

Look at this title screen screenshots from "Force Disruptor". It's an Atari imitation. The code is lost, but I still have some screenshots.

So you already know how to program and the screenshots are from a game you made on your own...

I know only little about Atari 2600, but i guess it has no graphics unit, probably you need to change the color of the cathode ray at exact the right moment driven by raster interrupts or something - ugh, that's a true pain.

Also, for vector graphics 8 bit systems are a bit slow, Elite on C64 had 10 fps (although this is full 3D so more math involved).

And are you aware you have to code in Assembler? (but looking there: http://nesdev.com/ i see there is a C -> 6502 compiler - i wish i had this when i was young. But i don't know if performance is close to handmade assembly code. However there is active NES homebrew, may be much more attractive than Atari.)

Or you could just wait for the upcoming Atari Box: Maybe it has open Linux OS, powerful hardware... sounds totally awesome.

If you are looking for the best opportunity to get a name arround people I suggest you first find out what console is played most actively, and over time you will have people interrested (the honestly curious gamer will treasure a piece even if its graphicly very simple i think) so even up to date consoles are not out of reach. depending on game engine and what you are used to. Best results come out when you create something for your self in the first place, and put everything else secondary

43 minutes ago, Robert Stoppel said:

so even up to date consoles are not out of reach.

You'd need a devkit... I don't think there's a homebrew community around modern consoles yet.