TASVideos

Tool-assisted game movies
When human skills are just not enough

Submission #7017: Winslinator's INTV USCF Chess in 01:21.31

Console: Intellivision
Game name: USCF Chess
Game version: any
ROM filename: USCF Chess (1981) (Mattel).int
Branch:
Emulator: BizHawk 2.4
Movie length: 01:21.31
FrameCount: 4872
Re-record count: 2288
Author's real name:
Author's nickname: Winslinator
Submitter: Winslinator
Submitted at: 2021-01-30 16:58:57
Text last edited at: 2021-02-24 17:01:55
Text last edited by: feos
Download: Download (2595 bytes)
Status: judging underway
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Author's comments and explanations:
Still not as fast as xQc versus MoistCr1tikal.


(Link to video)

Objectives

Difficulty Choice

Skill Level 1 was chosen for a variety of reasons. First and foremost is because the lower-right side button on the controller is the "Force Move" button, which forces the computer to make whatever move it has so far deemed best. The button only works once the computer has found at least one "suitable" move to make; the first "suitable" move is the one which would be selected by the computer on Skill Level 1. Therefore, there is no point in playing on a higher skill level when you could just press the "Force Move" button as soon as it is allowed. On Skill Level 7, the computer will not move at all unless the "Force Move" button is pressed. I could still select Skill Level 7 just for the fun of it but that would lose time to menuing and I did not want that.

Secondly, say there's a movie which completes an entire game on Skill Level 6 and does not allow pressing the "Force Move" button. It would be massively boring. The fastest checkmate I've found with Stockfish 12 makes the computer think for 7 hours, 12 minutes, and 54 seconds over the course of 30 painstaking moves. See the discussion for more info on this. In other words, Skill Level 1 is chosen not only because the computer thinks much, MUCH faster but it also makes lousier moves as I'll soon get into.

Routing

The goal is not necessarily to checkmate in the least number of moves but to deliver the checkmate that makes the computer "think" the least. For instance, the computer thinks for a cumulative 1:10 over eight moves in this TAS. I have also found a six-move checkmate but the computer thinks for 1:22 and is therefore not faster. Shorter "thinking" times are achieved by keeping the position simple. Giving the computer few options and not attacking with a lot of pieces simultaneously is a good way to minimize thinking times.

RNG

Moves are NOT determined stochastically. The computer's response to a position at a given skill level will be the same every time.

The Computer's Weakness?

The first thing to test for would be to see if the computer falls for any quick mates. I was surprised by how well the computer was able to defend every permutation I threw at it. Eventually, I found a way to make it crack: the computer values potential pawn promotion much higher than it should. In the case of this TAS, Black values getting a pawn to the second rank more than it values its own king! In the end, we have a game which looks like a longer variation of the Scholar's Mate.

Game Summary and Q/A

Move White Black Black's Time Commentary
1 e4 e5 0:07 King's Pawn Opening.
2 Nf3 d5 0:16 White puts pressure on Black's e5 pawn. Black ignores this and opts for the Elephant Gambit, establishing a pawn duo in the center and attacking White's e4 pawn.
3 Nxe5 dxe4 0:24 Both sides capture.
4 Bc4 Be6 0:38 White eyes up the f7 square. Black defends this with his light-square bishop!?
5 Bxe6 fxe6 0:46 Both sides trade bishops, but Black's pawn structure is now compromised.
6 d3 exd3 0:56 White sets up a distraction, offering to improve Black's pawn structure, which Black is eager to capitalize on.
7 Qf3 dxc2 1:08 The White Queen posts up on the f3 square which is no longer defended... but Black, who is obsessed over the idea of promoting, takes on c2 and does not notice that it's mate in one!
8 Qxf7# 1:10 GG

Q: Why waste two moves to first play Bishop c4 and then capture Black's Bishop? Why couldn't you just play d3 on move 4? A: Responding with literally anything else on move 4 prompts Black to play Knight f6. If Black plays this move, we are not giving checkmate anytime soon. Black's bishop must be captured because it is defending the f7 square, which will later be used for checkmate.

Q: Why couldn't you play Queen h5 on move 6 instead? A: Black would meet that with Knight h6, defending against checkmate. d3 is key to distracting Black and to lure their e4 pawn away from defense of f3.

Piece Movemements

There are also some meta strats going on with the cursor. A piece or square can be selected even if the cursor is on an infinitesimal protion of the square's right or bottom edge, or the bottom-right corner. This allows us to set all our pieces down quite early, and gives an advantage to picking up pieces if they're moving to the right (see moves 5 and 7; their movement distances are shortened due to how far to the right they are picked up).

The cursor becomes active for the player's next turn from the moment the computer starts moving a piece, even though it cannot be seen yet. This is why the cursor is always in the perfect spot when it becomes visible.

Special Options

The (8) key on the left controller allows the player to start as Black instead of White. I've also tested this pretty extensively and no quick mates can really be found. Besides, by going second, you're giving the computer an extra turn to think for which loses a lot of time.

You can actually adjust the skill level on the fly between the computer's turns. I also tested many variations to see if the computer would in some instances make a more dubious move on level 2 than level 1. In some cases, it actually did! But too much time was lost due to extra thinking time so we stayed on Skill Level 1.

Suggested Screenshot Any frame after the CHECKMATE! message appears


feos: Judging...


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