Competitive One-Check Chess

After playing three-check chess, I became very interested in analysis of one-check chess. Here is my idea for competitive one-check chess:

• Each player plays one game as Black and one game as White.
• Winner is the player who lasts the longest as Black (for example, score can be total number of moves survived in both games).
• If Black wins, it is an automatic win for the round (score of +infinity).
• Custom positions can be constructed to increase complexity. (If Black moves first, and White wins, then score is +infinity for White.)

Since both players play each side, it should be fair (at casual levels), although the player who is White second can get some experience from the first game.

I also think coming up with one-check positions itself would be fun to do.

One-check chess is supposed to be a forced win for White. (I haven't found the forced win yet, please comment if you know!)

One-check is a mate in 5 moves for White, starts with 1.e3. Example 1...e6 2. Qh5 g6 3. Qe5 (threat Qxe6+) and now 3... Be7 4. Qg7, or 3... Qe7 4.Qxc7, or 3...Ne7 4.Qc5

I saw that line too. I analyzed this on Lichess for a long time, and there is actually a mate in 4 for White with 1. Nc3.

Also 1. e3 Nf6 stops your idea of Qh5, and the suggested follow-up is 2. Na3

There is no need for long time analysis, have compiled an engine Onecheck.exe based on Fairy-Stockfish and it finds the mate in 5 in less than 1 second (you can download it at

https://filehorst.de/d/dzejGbfk 

it needs a GUI like Winboard where you chose the variant 1check )

Your move 1.Nc3 starts also a mate-in-5 (not mate in 4), and 1.e3 Nf6 2.Na3 starts also a mate in 5

Awesome, thanks for the link! I have been doing stuff by hand and its pretty fun but also using a computer is cool to check for mistakes. I'll take a look.

Anyhow, your engine might have a problem if it says Nc3 is mate in five. How does Black stop mate in four?

Here are my lines:

Onecheck.exe plays with Black none of this lines, but 1...e6. Feel free to try the engine for yourself

Holy moly what a move! I cant believe I missed that!

Edit: I got the engine working now, thanks!

So, literally can't be a variation as it is a mate in 4/5 simulator?