How is endgame theory developed? First of all, I am explicitly not asking for a list of endgame principles, nor am I asking for resources to study endgames from.

My question is: How does one develop endgame theory? The main motivation of my question is that I have been trying to study endgame theory for a chess variant (atomic chess, as it were) and there is precious little of it. I am quite literally writing new theory the deeper I study.

I'm looking for answers that could address either or both of the following points, in regular chess or in chess variants:


How endgames (regular chess or any chess variant) were analysed, organised and codified over the decades until we have our present-day knowledge;
How to study endgames, but without access to any books or professional games (just a chess set, a brain, an engine, tablebases, and lots of patience.)
How do you want to do it?

I know that sounds flippant, but that's pretty much the only good answer to questions along the lines of "How do I create something that no one has created?"

Chess endgame theory developed by people starting from very simple positions and identifying commonalities among them. Typically, endgames get classified by the pieces involved (Rook endings, minor piece endings, etc.) so I'd start with elemental positions that are clearly won/lost, see what leads to them, try and see common maneuvers to create them, etc.

From simple positions you create the building blocks for understanding more complex positions.

Rinse. Lather. Repeat.

An example is pawn endings. We started with simple concepts like the queening square, moved on to techniques like opposition, and kept building until we ended up with a theory of co-ordinate squares, which covered all pawn endings. Opposition, Triangulation, all of that stuff boiled down to being special cases, subsets within that theory. But it all started with atoms, from which we built molecules, and so on until we eventually arrived at an impressive, comprehensive, edifice.

There's no single uniform best way to approach something that's never been done. You try something, if it seems helpful you keep using it; if not, try another way.

By definition, there is no mapped out course to get you safely through uncharted waters.