All the games are websites — but they behave like an app when you add them to your home screen. No app store needed; it takes 15 seconds.
Open the game you want to add in Safari (must be Safari, not Chrome).
Tap the share icon ⬆ at the bottom of the screen.
Scroll down in the menu to "Add to Home Screen" and tap it.
Tap "Add" in the top right. The icon now sits on your home screen.
Open the game you want to add in Chrome on your iPhone.
Tap the share icon in the address bar at the top of the screen.
Tap "View More".
Choose "Add to Home Screen". The icon now sits on your home screen.
Open the game you want to add in Chrome.
Tap the menu (⋮) in the top right.
Tap "Add to Home screen" (or "Install app", depending on your Chrome version).
Confirm with "Add". Done — you'll find the icon on your home screen.