Yes, the problem I proposed was more of a puzzle than a game. I actually don't know if it can be solved. I don't know if it's possible to set up for a "massacre" wherein once pieces start to be taken, the _only_ moves allowed are captures until only the kings are left. I'm asking if a legal (if stupid) game of chess could progress without captures until a capture happens, after which only legal captures are allowed until only kings remain. I think that solving this would require hacking an existing chess program to first reject any captures, and then at some point, accept only captures. Since the capture game tree is substantially smaller than a normal game tree, it might actually be possible to store _every_ mini-massacre (sequences consisting of only captures), and hash it into a table. At 01:58 AM 1/9/2015, Guy Haworth wrote:

The two-phase chess 'game' seems to less than well defined, and - as far as it is defined - seems to be a puzzle rather than a game as there is only one results ... 'draw'.

Losing Chess, which prioritises losing and capturing men, is perhaps the nearest in concept.

There are various variants of it, but recent work on the mainline version of Losing Chess (ICGA Journal, Vol. 37-2 (2014) ) indicates that 1.e3 is a win for White.

Guy