TASVideos

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

Submission #7019: Winslinator's INTV ABPA Backgammon in 01:50.31

Console: Intellivision
Game name: ABPA Backgammon
Game version: any
ROM filename: ABPA Backgammon (1978) (Mattel).int
Branch:
Emulator: BizHawk 2.4
Movie length: 01:50.31
FrameCount: 6610
Re-record count: 9550
Author's real name:
Author's nickname: Winslinator
Submitter: Winslinator
Submitted at: 2021-02-02 21:13:39
Text last edited at: 2021-02-24 17:02:06
Text last edited by: feos
Download: Download (3803 bytes)
Status: judging underway
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Author's comments and explanations:
It's Backgammon on Intellivision! Don't know how it's played? Click here to learn the rules.


(Link to video)

Objectives

Strategy

I guess the best theoretical strategy would be to roll double 6's every time and win in nine moves. However, in this TAS we have to make the AI take its turns as fast as possible and deal with sometimes busted RNG.

So how do we get the AI to take the shortest turns? Give it nowhere to move. Therefore, we should aim to hit one of the AI's checkers early to make it easily accessible to future hits in our home board, and immediately start closing our home points. The more home points we close, the higher the likelihood the AI will be unable to move and we save lots of time!

RNG

After the player moves their checkers, the frame on which the Enter button is pressed to confirm their turn has ended is what determines what the AI will roll AND WHAT YOU WILL ROLL ON YOUR NEXT TURN! This is the principal reason why RNG is so difficult to manipulate in this game.

Sound effects are used to represent dice being shaken in the dice cup or rolled onto the table and their durations last a random amount of time. Just another annoyance to add on top of getting the correct roll between the AI and the player... now we gotta worry about how much time the very act of rolling takes!

Checker Movements

The (0) key on the controller is the "Move Two" button, meaning if we are smart in how we arrange our checkers (i.e. arrange them in even stacks when possible), we can save some moves.

More insignificantly, some attention was paid to the time it takes checkers to move from one point to another. Checker speed is constant so we can just use distance travelled as a time reference. Take moves 4 and 6 for instance where a total of seven checkers are moved from the 14/13-point to the 8/7-point... in other words, they were all moved there via a 6 roll which takes the most diagonal path between these points, saving time.

Game Summary and Q/A

Turn White Black Commentary
1 6,5 5,1 White consolidates six checkers on their 13-point so "Move Two" can be used for all. Black is forced to make a blot with their unlucky roll.
2 4,6 6,2 White hits. Black enters but is vulnerable.
3 6,4 2,6 White hits again and closes their 2-point. Black cannot move.
4 6(x4) 6,5 White advances four checkers to the 7-point. Black enters but is vulnerable yet again.
5 3(x4) 2,6 White hits and closes their 5&4-points. Black cannot move.
6 6(x4) 5,6 White advances one checker to the 2-point and two to the 7-point. Black cannot move.
7 4(4x) 5,2 White closes their 3-point and is now ready to bear off. Black cannot move.
8 6(4x) 5,4 White bears off the four checkers on their 6-point, opening it. Black cannot move.
9 5(4x) 3(4x) White bears off the two checkers from each their 5&4-points, opening both. Black cannot move.
10 2(4x) 4,6 White bears off the three checkers from their 2-point, opening it. Black finally gets to enter again lol
11 6(4x) White bears off the four checkers from their 3-point, winning the game.

Q: Why did you not roll doubles on turns 1-3? A1: The game simply doesn't appear to allow doubles to be rolled on the first turn. A2: Only if black rolls 2,1 5,1 6,2 6,3 or 6,5 will they be in a position to be hit, and White must also get a roll which actually hits blacks checker, meaning if we want doubles they must be either 4 or 6. Since White's roll is tied to Black's roll, this is really difficult to all line up and so it's faster to just take the 4,6 route. A3: Double 4's or 6's didn't come fast enough.

Q: Why get double 3's and 4's on moves 5 and 7? A: This is simply to close up all points possible so that Black has a higher potential of losing turns.

Q: Why did you let black enter on turns 2, 4, and 10? A: On turns 2 and 10, only one point was closed, meanining it would be a 1/36 chance for Black to be blocked which must be followed up by a decent roll for White which did not happen in a timely manner. On move 4, it was the only way the game would give me double 3's which had to be rolled that turn to close off the 5&4 points.

Q: On move 3, why did you move the checker from the 6 point before the one on the 8 point when if you did it the opposite way you would've saved a small bit of travel distance? A: I would've rolled double 6's at the same time for the subsequent turn regardless. I actually chose to move the checkers in the order I did because that saved 1 lag frame for whatever reason.


feos: Judging...


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