I analysed my difficulties more and noticed that the negative happiness spiral is always the following:

1) Happiness is going doing.
2) Raising happiness would require buildings which need a high number of people (parks and restaurants).
3) Because of the happiness level, I can't get enough people to join my colony to raise the happiness.
4) Happiness keeps going down which is the end OR I ran out of food because farms also require people.

Improvement suggestion: Adding a building option to improve happiness which doesn't require people at all.

Most often I seem to get into this chain reaction: happiness is getting low and I start to lose people (or not getting enough of them) which leads to everything failing OR to increase happiness enough I need to use quite a lot of resources to cover the building costs. I tend to start running out of food at some point. Often it takes most time to get enough fertile soil for farms, depending on the map of course.
However, it's also possible that I haven't learned the right balance yet...

To my opinion, the costs of buildings is a lot more balanced now than in the previous version.

PS: I've been only playing on "normal" mode.

I've now played the 0.3 version several times. I really like it even though it feels quite challenging after the first version and I still don't get all the things affecting happiness. But hey, colonizing a new planet is not fun. :D

One annoying bug to fix in the future versions: When terraforming is selected, you have to be extra carefull NOT to have some building construction selected at the same time. If you click to do the terraform you might end up building something by mistake even if you thought you were about to do terraforming.
Improvement suggestion: When selecting a terraform piece, deselect all building pieces currently selected and vice versa to prevent accidental construction.

I've done this mistake by accident myself several times now.

Go ahead! Happy to help! :)

I was able to run the game on my Mac with this trick given by the OSX user guide (which also means you trust Andriy 100% not running any malicious software with the game):

Open an app by overriding security settings

You can open an app that isn’t allowed to open by manually overriding the settings in Security & Privacy preferences.

1. In the Finder on your Mac, locate the app you want to open.

   Most apps can be found in the Applications folder.

2. Control-click the app icon, then choose Open from the shortcut menu.
3. Click Open.
   

   
   

   The app is saved as an exception to your security settings, and you can open it in the future by double-clicking it, just as you can any authorised app.

This game was a nice surprise. Well crafted. I've had fun with this on several days. Few comments on how to make it even better:

• It's a bit unclear how the terraforming pieces work when you start playing. This applies especially when using it to other tiles than mountains like wasteland.
• Deconstruction item could have some info about how it's beneficial or do you gain anything back, such as metal, when using it.
• Maybe some environmental settings and additional factors such as storms or aliens to make it more interesting. :D