An AI for 2048 — Part 2 Cyclic Blind Strategies

In my last post, I described how to play 2048 and reported the results of some simple simulations.  Namely, I reported the results of two very simple strategies:

  • Random play will achieve an average ending tile total (AETT) of 252 and usually the highest tile will be a 64 tile or a 128 tile (about an 85% chance of ending with one of those).
  • A pure greedy strategy where the player just tries to make the largest new tile possible results in an average ending tile total (AETT) of 399 and usually the highest tile will be a 128 tile or a 256 tile (about an 87% chance of ending with one of those).

 

Blind Strategies

Perhaps surprisingly, there are “blind” strategies that will do even better than the pure greedy strategy.  Blind strategies are strategies that ignore the current state of the board.  I tried two types of simple blind strategies “biased random” and “repeating sequences”.  I will summaries the results of the biased random trials in my next post.

The simplest repeating strategy would be just hitting the same key every time—down, down, down, ….   Of course that does not do well.  Nor would down, up, down, up, ….  So the simplest repeating strategy worth trying would be down, right, down, right or some other combination of horizontal and vertical moves.  I ran 100 games for every possible repeated sequence of two to four moves and found that the best of these sequences was down, right, down, left  or a version of that sequence in disguise.  The results are captured in the table below.

Notice that restricting your moves to only two out of the four possibilities does poorly.  The Down, Left, Down, Left… strategy had an average tile total of only 44.38 at the end of the game and that strategy never created a tile above 64.

The best strategies were down-right-down-left or that same strategy in disguise (dlul, dldr, and drur are really the same strategy).  Notice that this strategy does better than pure greedy which had an AETT of 399.

move sequence AETT Largest Tile
dl 44.38 64
ddll 46.98 64
drrd 47.98 64
dld 51.18 64
ddrr 52.68 64
drdd 53.32 64
dll 53.46 64
dlld 54.32 64
dr 55.76 64
drd 56. 64
ddrd 57.48 64
dldd 57.66 128
dlll 58. 128
ddl 58.5 64
ddr 58.58 64
drr 59.9 64
drrr 60.56 64
ddld 61.62 64
dddr 66.78 64
dddl 68.46 64
dulr 262.44 256
durl 266.8 256
drlu 267.38 256
dlru 273.4 256
drlr 290.96 256
drdu 295.4 256
dlrl 298.5 256
duld 298.58 256
dldu 307.06 256
duru 308.8 256
dllr 309.32 512
dlrr 312.56 256
dudr 313.38 512
druu 314.58 256
duul 315.74 512
dudl 315.82 512
dulu 317.16 256
dluu 322.48 512
ddul 323.92 256
dlud 325.92 256
ddur 326.6 512
ddru 328.5 256
durd 329.12 512
drud 333.7 256
drll 337.92 512
ddlu 338.6 512
duur 345.62 512
dlu 345.88 256
dru 348.1 512
drrl 348.26 512
dur 352.72 256
dul 354.64 512
ddrl 357.3 512
dlr 361.1 512
ddlr 372.24 512
drl 373.32 256
drru 375.3 512
dull 377.38 512
dllu 379. 512
durr 385.38 512
dlrd 404.16 512
drld 404.6 512
drul 435.72 512
dlur 440.06 512
drur 614.9 512
dldr 620.36 512
dlul 627.06 512
drdl 686.28 512