[tialaramex]

"Just by doing that" you can't even begin.

The problem is that you lack an evaluation function. Let's consider two of those 100 possible moves. Your rook could take this opposing pawn, or, your own pawn could move forward one space. Which is better? Why? Neither of them immediately wins the game, but we must pick something. In a smaller, tighter game, like Tic-Tac-Toe we could crank our exhaustive search until we discover that this opening move leads to a possible win... but the search space in Chess is categorically too enormous for that.

Both Google's Alpha Zero and simple human play encourages the belief that a good evaluation heuristic is essential. The evaluation heuristic looks at a board position and it doesn't recommend a move it says something like "I rate this position 0.418" where 1.0 is "I'll definitely win on my turn" and -1.0 is "My opponent wins on their turn". Google's engine contemplates relatively few possible moves (for a computer) but the results are striking because it's looking at _good_ moves more of the time rather than wasting a lot of time thinking about moves that are a bad idea.

This seems obvious, but, well, learn chess and see for yourself.

[foldr]

Yes I'm aware that you need an evaluation heuristic. My point is that you don't need a particularly good one to be able to beat an average intelligent human at chess. (After all, most humans don't have very sophisticated chess position evaluation heuristics, and they are able to examine vastly less of the search space than a computer.) Beating Kasparov is another matter, of course.

Here's an example of a simple chess engine that is good enough to beat amateur human players at least some of the time:

https://news.ycombinator.com/item?id=8133125

[gaius]

Or even https://en.wikipedia.org/wiki/1K_ZX_Chess