Glad that the bigbrainz goblin game is going down well! Mostly 7-11 year old boys love it but I've had some girls tell me it is "too scary"!!
Tip:
If you still "ration it" whilst letting him play on it quite a lot (eg only 20 mins at a time or whatever) it will be likely to keep its appeal and street cred for longer!!
Some other things you could try:
Once he has got to the sage of recalling a table ( even if very slowly) try getting him to recite it while throwing a foam ball or juggling ball (or small teddy!) up and catching it. One throw for each sum iyswim. It helps them get in a rhythm with saying it and also do it more automatically. Then you can "play" between you so you throw the ball to him and say 4x3 and he has to throw it back and say 12.
Boys particularly seem to like this one as they can move physically while learning!
Get some bath crayons - but keep them especially for learning tables, not for general play and as a "special treat" let him write out the current table on himself or the tiles at bath-time. ( He may - or may not feel too grown up for this one?) One mum I know got her son to practice saying tables at bath time and she would flick him with cold water if he got one wrong (He was the sort of kid who found this hilarious and a great game!! Would not work with all kids though!)
Get some chalk and let him write the answers to the "current" times table large on the drive or patio ( if you have such a chalk-able surface). Then you yell out a sum and he has to jump onto the right answer.
If you have a trampoline you could try getting him to bounce whilst reciting a table. Again the movement and rhythm seems to help them learn!
I agree the penguin one is for when they have learned them thoroughly but need to speed recall!
Have fun!!