I’m moving!

Dear reader,

While I’m busy moving this site to a new place where I can give you a better overview of the content (and revisiting my reviews as I do) there’s no new update here.

If you’re daring, head over to the new place:

https://gammonrants.org/

Content there is growing fast, but so far it’s still only three reviews…

I’ll keep you updated once I’m more or less done.

How strong is that backgammon app? The big table

Update Sep 8,22: Backgammon KG added (PR 5.7 after 11 games)

Part of my app reviews is a solid test of the respective AI's playing strength. If the app supports it (and a good app should!) I play a couple of matches against it, export them to a file, and let Extreme Gammon 2 (PC) review our match on highest Roller++ level. This should give the reader a good understanding of the app's rating in "PR" (performance rating) points.

Apps that don't support export are harder to rate - I play something like a 3pt match on my iPad and transcribe it simultaneously into XG2, which is an exhausting process. Fortunately the apps that don't export are typically weak, so a rough rating is enough.

So, why not put them all together in a big table for you to compare? Here we go, (iOS) backgammon apps sorted from best to worst. 

 

 

 

Please note: this table is work in progress; I'll add new apps as time permits.

Please also note: it's difficult to rate the strongest apps; it might be unfair to rate a BGBlitz based app with XG2 only. I'm planning to compare the best 3 or so apps by analyzing a good number of matches with XG2, BGBlitz and GnuBG some day...

About the PR rating

PR ratings reflect how big an error on average you make per move, compared to the optimal move. The lower your PR, the better you're playing. XG uses the following names for the different PR ranges:

• 0,0 - 2,5 = World Champ 
  
• 2,5 - 5,0 = World Class  
  
• 5,0 - 7,5 = Expert 
• 7,5 - 12,5 = Advanced 
• 12,5 - 17,5 = Intermediate 
• 17,5 - 22,5 = Casual Player 
• 22,5 - 30,0 = Beginner 
• 30,0 and above = Distracted

The arguably strongest human backgammon player, Masayuki Mochizuki ("Mochy") has a PR of slightly above 2. Some sites call an average PR of less than 1.5 “superhuman”, which I’m also doing here.

The most embarassing extracts from the worst match I played in a long time

With the reasoning "if these positions were too difficult for me to find the right move they might also be interesting for you to see" I'm herewith showing you a couple of interesting positions from an embarassingly poor 5pt match I played against True Backgammon (iOS) on BGBlitz-2 (ie superhumanly strong) level.

Enjoy :-)

 

Blue to move 21

Things started out poorly in game 1, where I made my first 0.15 blunder in move 2 already. What should I have played here?

I wanted to play 13/11, staying out of direct hit range from his checker on the 4. So I entered on 24, playing BAR/24 13/11. 

Obviously, given that white has only a 1 point board, I should have played bold and hit on the 4, accepting the >50% risk (I counted 19/36 hitting numbers) of being hit for the chance of making the 4 point in the next roll. XG2 says the correct move is BAR/24 6/4*, followed by BAR/23, 6/5 (-0.074) and my AR/24 13/11 (-0.145)

Lesson to be learned: play very bold against a 1 point board.