This is currently written for the release version of Dorpie, it might get updated later for new achievements and changing requirements, I'll probably try and update it every once and a while.

Many of these achievements are either extremely easy or are in a "series" of achievements where one is just a higher number than the one before. But for sake of completeness I added them all with a quick explanation on how to get it.

I recommend you try and get all of these without creative mode, however, using creative does allow you to get achievements.

All of the "Pillar" type blocks are free to place, useful for building up cheaply and you can always replace them with full blocks if you need the sides for ledges or arches.

"Place 50 units in a single playthrough."
Simply have 50 objects in one Dorpie.

"Build to a height of 5."
Simply have a structure that reaches up 5 blocks, you don't need anything above that to get the achievement.

"Place a garden of size 10."
Have 10 garden tiles connected, they don't need to have a gateway.

"Place 10 connected roads."
Have 10 road tiles connected, they do not need to connect to houses or anything else.

"Place 200 units in a single playthrough."
Have 200 objects in one Dorpie.

"Build to a height of 10."
Just as in the "Tower" achievement, but up to layer 10.

"Have only two entrances on a closed road network, in a Dorpie with at least 10 homes."
Have 10 homes connected to each other, then put 2 more with a road between them, disconnected from the first set.

"Place 50 connected roads."
Similar to "First Steps", but with 50 roads.

"Build an arch over an unbuildable area to create more building space."
The edge of the map isn't an even square, use an arch over a gap to get the achievement.
It should look like the one on the right.

"Take a screenshot of your Dorpie."
Hit F12. AT TIME OF WRITING THIS DOESN"T ACTUALLY TAKE A SCREENSHOT, USE OTHER CAPTURE METHODS TO SHARE A PICTURE.

"Place a garden size of 80."
Its an upgrade to the "Garden" achievement, but with 80 interconnected tiles.

"Have 10 roads running over other roads."
You need to use arches to place 10 roads over other roads, elevation doesn't matter.

"Have only one entrance on a road network that is at least 20 units long."
Have only 1 house connected to at least 20 interconnected road tiles.

"Place 500 units in a single playthrough."
Yet another "place x amount of y". 500 objects in one Dorpie.

"Cover an entire map in a garden."
Use a small map size and place enough garden tiles to cover all buildable areas, using arches to go over the boundaries doesn't increase the requirement.

"Cover an entire map with garden, that is at least 3 levels above the ground."
Works the same as the previous "Central Park" but all the garden tiles need to be 3 levels up. Easy way is to just place tall blocks and arches to have a full build surface for all the gardens.

"Have two distinct road networks, with at least 25 buildings per network."
Have 2 sets of roads, each having 25 houses connected to them to get this achievement.

"Place 1250 units in a single playthrough."
The largest one in the "Village" series, difficult part is getting here without creative. Definitely use a large map and heavy use of pillars.

"Place X structures."
Architect - 1000
Engineer - 10000
City Planner - 100000
I grouped these as the advice is the same, just keep playing. Creative is definitely the easiest but also the most boring,so just keep building Dorpies and you'll eventually get all the way to "City Planner"