I got my beta key yesterday, tried it last night and only intended to look for 30 mins or so, but was on until 2am! really liking it.
Was a bit tricky to figure out what I was doing, had to start over a couple of times, the 'how to play' guide wasn't much help.
At the start, the aim is to clear space so that the two people can built a house, however moving the ground uses up belief and you don't start with much (number at bottom left). You can gain extra belief by removing Stones and Trees, if I recall correctly, I think you can create enough space by removing the rocks and trees near them - however if you do need to move the land to make room, just left click and drag. When enough space is available, you will see the outline of a building plot appear, then the people will settle there automatically.
Once they have settled, a flag will go up once they have produced an additional person, click on the building to have that extra person leave the building. At this point you should have received a notice that your influence has expanded, so clear more space for the new person to build a home.
You will also see a purple sphere appear above houses, this is belief, click on it to collect the belief.
Note: people don't survived very long without a home or an activity - they seem to lose health, however clicking on them will restore their health.
Much of the games goals are achieved by finding cards, these cards will either provide an immediate benefit (like the Land Expansion card), will be an objective (such as the science or society cards), or will be a resource card (such as Timber, Stone). Objective cards require you to gain certain amounts of resource cards in order to unlock their reward (such as better housing).
You can find cards in chests scattered around the landscape (there is one near where you start), however sometimes they are buried an have to be dug out - you can spot them even if buried as they have 'things' floating around them that can be seen on the ground where they are buried.
In the top left you have a population counter, this shows how many you have and your next target. When you reach the target you will get another card, in the early stages these are mainly Land Expansion cards
You will also find ruined alters and monuments around the landscape, once your people find find they will rebuild them, which will also generate you a reward card.
The aim (as far as I can tell) is to grow your civilization through the ages - you progress through the ages of civilization by completing the objective cards. Think I've got to the third age, not sure how many there are available in the beta though
At a certain stage you find a large monument that will open up the PvP options (though right now I'm either being stalked by a girl called Amy, or it's only AI battles at the moment). Here you choose how many of your followers you want to take into battle (which seem to come out of your current population), then the battle begins on a separate landscape. The goal here is to wipe out the opponent (your people and their people will automatically fight when they see each other), so you need to have your people build lots of houses and breed so that you out number them.
Winning these battles also provides you with reward cards, some of which I don't think you get in the normal flow of the game (such as the red headed wild man)
Hope that helps.