Happy Zephyr is a mini-game in Warframe. To get access to Happy Zephyr, you will need to purchase the Ludoplex from Cephalon Simaris. This will cost you 50000 Standing. You will then need to buy the Happy Zephyr mini-game from Simaris for 25000 Standing.
If you own Zephyr or Zephyr Prime, you can go to their Appearance tab in the Arsenal, and click on the Z loadout tab in the top left corner to play the game.
You can earn Standing with Cephalon Simaris by finished daily bounty challenges. To get these, you need to visit Cephalon Simaris on any Relay, and he will give you a synthesis target to track down and scan. You will also earn a small amount of Standing each time you scan any enemy during a game.
When you purchase the Ludoplex from Cephalon Simaris, you need to place it in the Orbiter as a decoration. Open your main menu, then go to the Equipment, Orbiter, and choose the option to decorate the Orbiter. Find the Ludoplex and then place it where you like in your Orbiter. Interact with the device and select Happy Zephyr from the options.
Happy Zephyr is a riff on the old Flappy Bird mobile game. You need to get a continuously flying Zephyr across the screen, avoiding obstacles. This is a quick and easy to play mini-game; all you need to do is stop Zephyr from hitting any obstacles, the floor, or the ceiling. All you need to do is hit the space bar or jump button to keep her flying and avoid all the obstacles. If you hit them, you are instantly killed.