IDK if game devs "Mechanistry" are "indie", but their single game, Timberborn, is the best colony building / survival in a long while. Functionnal and tons of fun but still in developpemnt. Pretty enough without needing a good computer.

Silly fun colony building with beavers. Controls are intuitive. Tutorial will get you started.

Setting : The land is a barren wasteland aside from seasonal streams flowing into pretty rivers. You are beaver God. Manage your beavers to chop wood, store water, build dams, grow crops, build houses, bridges and industry, make babies, expand. Make your beavers happy and well fed and they work faster.

Ambitious irrigation projects are fun ( irrigation towers are shit though. Blow a hole with dynamite and fill it with water ).

Easy and Normal modes = relaxing.

Hard mode = the drought can actually kill you if you don't manage well.

Costum difficulty : craft your dream apocalypse.

You can fall back on a previous save if you screw up with a drought season.

Next update will add map previews and costum key binding. Also a new feature : toxic sludge will flow from streams to raise difficulty and keep hydro-power working during drought.

Singleplayer game. No "online or it stops working" bullshit. Install it where you want from a USB key and play.

A small map can run on a potato laptop. Perfect for a bit of fun anywhere.

Mid-range integrated graphics laptop will run all maps well, unless you want flawless max speed 300+ beavers colony.

It goes on sales for special occasions, like for the holydays. ~30 bucks regular.

If you buy from GoG, you get the full install, no "you have to launch Steam too" BS.

It's also easy to find on torrent sites ( which is how I tested it before buying ).