Goodgame Empire (free registration required), by Goodgame Studios, is the sort of casual strategy simulation meant for players looking for something to pick up for a few minutes at a time and a way to antagonize other players through good ol' fashioned siege-ery. You're given your own castle and surrounding kingdom you're in charge of building from the ground up, and it's up to you to keep your resources high so you both have enough wood and stone to build new structures and defenses with, and enough food to feed the growing army you'll be training. You'll need cash too, of course, which means building houses for people you can collect taxes from to come live in. Why, what do you need an army for, you ask? Well, you could just use it to defend yourself from and attack bandit hideouts, or you could sally forth under your new banner and sack some rubes, yo!
Goodgame Empire is structured like a Facebook game, in a way. You'll be given tasks and objectives by the various members of your kingdom, and completing them grants you rewards as well as expands your castle and the things you can create. Everything takes time, however, so you'll either have to wait for an objective or order to be completed (which can be anywhere from seconds to hours of real time), or spend rubies to finish the task instantly. Rubies are granted as you level up from experience gained completing tasks or found as treasure, or you can spend real money through microtransactions if you're impatient, though it isn't necessary to play the game. Though it seems simple initially, running your kingdom quickly becomes more complex as you have to expand your land, develop and assign you defenses, recruit and train different types of warriors, and more. Fortunately, the game's helpful advisors will walk you through everything every step of the way.
Goodgame Empire walks the line carefully between casual and simple, with gameplay that's less challenging than it is simply involving. The time-based construction and objectives won't be for everyone, since it means you both can't really play for long stretches at a time, and you're forced to check back frequently to make sure everything is in good working order. At the same time, however, unlike a lot of games with similar gameplay models, Goodgame Empire not only offers you a lot to do and has a surprisingly high quality design, it doesn't nag you to spend money on it, or feels like it's trying to force you to do so by ridiculously padding the costs of things in game. While it's true to get the most out of it without paying you'll want to be playing frequently and for a long time, there's a surprising amount of things to do and see to keep you doing so. Random encounters with highwaymen you can bribe or battle, research trees, regular treasure discoveries and rewards, artifacts to forge, new kingdoms to travel to, and more ensure that there's a lot to do.
Though you are protected from being attacked by other players for seven real time days once you start playing, it's sort of disappointing that you can't choose to play only single-player if you aren't interested in competitive play, even if it were made a permanent choice. The game itself doesn't really have much of a story beyond "get bigger, smash everyone else!", but its beautifully drawn with colourful style. Chances are you'll find it still gets a little repetitive, especially with a lot of its content locked until you reach staggeringly high levels, there's still a massive amount of content to be had, and what feels like an impressive focus on quality. If you're looking for an engaging casual simulation that fits into your spare time with enough to keep you busy for a long time, Goodgame Empire is definitely work checking out.