Best Offline Games for WP?

Hi guys - I used to post here under a username but i've decided to switch over to my real name (because hey why not =D)

Anyway - I would love some advice on some games.

Currently I go to the gym for about an hour every day. The first 20-30 minutes is cardio which basically consists of me using the steps machine. As an L920 addict, my two hands are normally playing with my phone.. This requires a fair amount of balance.

Now the problem is, my gym has no reception so I can't play online games on my phone. I also can't play vigorous games like asphalt 7 which would probably cause me to fall off the steps machine. I basically need a fun game which is engrossing enough to make 20 minutes fly by and is enjoyable enough without a multiplayer mode.

So far I've tried hex war (great but limited)

angry birds as the back up

drag racing (great but then it has really obscene requirements at the higher levels which led me falling prey to making an in-app purchase =o)

bullet asylum (awesome music and 'completed')

robotek (also completed)

monopoly - easy once i figured out how to game the AI

oh i tried civ revolutions also but gave up after about 5 min. it's much too simple compared with the original civs and also much too complex to play on a phone (for me).

having said that - are there any sim city type phone games?

So recommendations guys, please!