There are 13 Achievements in total.
You can confirm them in the in-game Settings menu (gear icon on the desktop).

Complete the numbers game (inside programs folder). Match 4 consecutive numbers in the grid horizontal, verical, or diagonal to win. It's a game of multiplication of the inner and outer circle digits. You have better chances of winning if you start with a central number.

Win a game of pong. Find pong in the programs folder and open it. Then, click the microphone icon top right. Pull on the jack that comes down. The trick here is that you actually need to use a real microphone. Blow into it/make noise to lift the paddle. It may take a few tries to get it right. Score 5 points to finish a game.

Click the Bluetooth icon upper right. Arrange the blue dots to draw the actual Bluetooth icon. After you do this, you'll get an unlock from the desktop showing you more shapes to draw. Complete all the figures to get the message.

Open the battery mini-game upper right. As the name says, intentionally lose at 5 points. This is easier if you avoid collecting the stationary green dots.

Easiest one. Allow the game to idle, and a screensaver appears. Continue to wait some time until you hear a chime, this triggers the achievement.

After completing the portals game (open portal 1 & 2 at the same time, and walk a path to collapse all the white boxes) then a central dot appears on the desktop. Click it to go back to the password screen.

The puzzle involves all sorts of combinations of the original password digits 8,7,3. Some digits repeat.

Here is the list:
733
737
783
787
833
837
883
887

After you unlock a node that shows a black book turning a page, click the lower right corner of the desktop, and keep doing so until you arrive back on the desktop as before. This unlocks the achievement.

Type clippy on the desktop. Small black circles will appear at the top of the screen to indicate correct entry.

Click and drag anywhere on the desktop. when you release you will get a percentage showing how close to a perfect square you drew. Keep trying and at 100% it will pop.

Find support from the drop-down red ribbon upper left. Copy the shape of the icon (light up all segments except the very bottom) to get the achievement.

After turning all nodes on desktop green, you'll meet the blue screen. Press W as instructed to wake up and get the achievement. This one's hard to miss.

Open mines in the program folder and complete one round. It's reverse minesweeper, you want to click only on mines. Right click will mark spaces empty to help you keep track.

After completing the Ford's triangle puzzle (stacking the desktop icons by their sum), the new unlocked circle has a switch. Click it, and it shows yunus' triangle, requiring subtraction. Construct the upside-down triangle, and again touch the red ball to block "1", and you receive the achievement.

The solution is:

This isn't tied to any achievement, but at the "conclusion" of turning all the nodes green on the desktop, one final mystery remains. In the circle that shows you "friends" to find, the central dot remains white.

It contains a message that sounds sort of like the riddle of Sphinx, but not quite.
"What walks on two legs in the morning, afternoon, and evening?"

It is unclear what this means, where to input a solution (if it exists), nor what may or may not mark the end of the game.

If you know the answer, please share.
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Thank you for reading. This concludes the guide.