(Reserved for eventual Q&A). Post your questions in the comments below.
4PC Engines! Info + Q&A
Over 100,000 games and still blunders right in the opening. I guess there are lots of 3 (or more) moves tactics it has never experienced in training.

how do you play with them? ( i think i was told that they need to invite me)
The games hosted by the engines will be given a custom title (i.e. "Phoenix Challenge"), and are available to any player. If you see these games, and want the chance to play against an engine, join to try it out!

its good for education purpose But do not put efforts and work on make them stronger these will then soon become machine battle there are good human players who is still playing at least until theory s is there do not involve engines they will ruin freshness just like its been ruined in 2 player
"as i notice every title chess player wish engine where not there it never too late "
Ruin freshness? Don´t worry, not a chance, even if you lived for centuries and played millions of games.

Wait, you can program chess computers with C?
chess programs, not chess computers lol

its good for education purpose But do not put efforts and work on make them stronger these will then soon become machine battle there are good human players who is still playing at least until theory s is there do not involve engines they will ruin freshness just like its been ruined in 2 player
"as i notice every title chess player wish engine where not there it never too late "
stronger 4pc engines are inevitable.

How can i play against these?
how do you play with them? ( i think i was told that they need to invite me)
The games hosted by the engines will be given a custom title (i.e. "Phoenix Challenge"), and are available to any player. If you see these games, and want the chance to play against an engine, join to try it out!
Please, if you're not going to read the original post, at least read the comments and replies. Or if you don't want to do either of those, don't ask questions that will have been answered in both.
You don't need a computer to tell you that 4-Player Chess (4PC) is more than just twice as complex as its 2-player counterpart. The game of 2-player chess has been around for centuries, and it's been decades since us mortals could defeat the best of what computer engines can do. Stemming back to Kasparov's 1997 defeat at the hands of IBM's Deep Blue, man is no match for machine in one-on-one chess. So the question arises, how do engines perform in 4-player?
The resources of the 4PC community are far less than what's available to the teams behind DeepMind's AlphaZero, Romstad, Costalba, & Kiiski's Stockfish, or Komodo, by Kaufman, & Dailey, although that hasn't stopped some AI-savvy programmers from building some very talented engines. Currently, there are 3 engines, each in various states of revisions and self-learning. As of yet, the engines are only learning how to play as teams. FFA and Solo are much less predictable, and the challenge of programming an engine increases exponentially as the element of luck and randomisation increases.
These engines have the ability to host rated or casual teams games within 4PC, and will only ever be partnered with themselves. Aside from the fact that it's a bot controlling the moves instead of a human, the gameplay, rules, ratings and mechanics are the same as usual. The games hosted by the engines will be given a custom title (i.e. "Phoenix Challenge"), and are available to any player. If you see these games, and want the chance to play against an engine, join to try it out!
Prior to any of these engines being developed, our very own developer from 4PC, @spacebar, created a two types of bots for testing purposes. These are the Mr.Random Bot and 4-Comfuter, which do not play games on their own, nor can they be invited to rated games.
Let's meet the engines!
Terminator by @Tony
Machina by @kooser6
PhoenixZero by @omatamix
A 4th engine, as a collaboration between @omatamix, @kooser6, and @GTSWPM150 is in the works, under the title of ZivaZero. One area of focus for this new project is openings, and in particular, discovering new, more dynamic teams openings. As of right now though, we'll have to wait in anticipation!
Many thanks to the creators and collaborators on these projects, both for their investments in 4PC engine creation, and specifically for their contributions to this article. I'm sure I speak for all of us in the 4PC community, when I say we are excited to see what the future holds.