Currently, I know several suicide chess engine that have been released under open-source license.
Nilatac and Catnail have been finally release under GPL v2. At least you can now see how he’s doing his search. Unfortunately, his development is frozen since 2004. I wonder if any C programmer have made / try to use his code, maybe to release a stronger engine. You can find his source code there
Sjeng is a strong chess engine, it play Suicide, but others variants and regular chess. Variants are support up to version 11.2 . Sjeng became a commercial program sinice version 12.13. IMHO that’s bad, I wonder how strong Sjeng became after, specially in suicide variant. You can download the program and the source code there
Recently I talk about the nakshatra engine, in my How to win series. I discover after that, it’s a open-source engine. The good news is that the programmer is still working on it. His last commit was only 12 hours ago. On his site, it look like he want to support regular chess too. You can see his website there
And the last one, my own suicide chess engine, Nessegrev. Unfortunately, I think that in the current state of the source code, Nessegrev didn’t work well, still some bug in it. But I still working on it🙂 You can take a look to the source code there
If you know any others open-source suicide engine please let me know, so I’ll be able to add them here.