This is my current mobile/casual fix:
http://www.rivalkingdomsgame.com (Android/iOS)
It's like an advanced Clash of Clans, but requires more time as it has a much heavier emphasis on attacking, Clash encourages at least 2 attacks per day. This one encourages many more than that, rather than using resources to build your army, you just attack with what troops you have capacity for up to once every 20 minutes with a stack of 5... So if you want to do near max efficiency, do 5 attacks every couple of hours. Unlike clash, there is no searching through dozens of targets, you get one and you attack it. There's a fast forward button so easy targets can get demolished in seconds. In addition, it works on streaks, your first battle will always be one with just a single defence, but when you get to a streak of 10 wins or so, it starts to become difficult -- resource rewards get progressively higher until you lose, and mystery boxes occur every second battle.
Overall, Rival Kingdoms is a more advanced version of clash, but requires 20-40 minutes a day for, reasonable progress... Spread out over 4 or 5 sessions of course.
I would love to see a Utopia mobile app, I checked out the game recently, and it is really dying down to nothing, only a few thousand players left. Casual browser games are almost a thing of the past.