Taking turns, or playing at once
There are two ways to share a screen. In the turn-based games, 2 player chess, Checkers and the dots game, you pass and play: the board stays still, and the game shows whose move it is, so nobody has to turn the device round. In the arcade games, both players play at the same moment, each on their own part of the screen.
Air Hockey puts a goal at each short end. Hot Potato and Whack-a-Mole cut the screen into a zone per player. Snake gives everyone a joystick. Tilt Run is the odd one out: one device has one tilt, so two people hold it together and steer one marble through the maze.
Phone or tablet
A phone is enough for two in every game here except Spillover, which needs a tablet so each half has room to draw. A tablet gives more room, and in Snake and Whack-a-Mole it seats up to four people around one screen.
Lay the device flat between you and sit at its two ends. Bots can take a seat too, so one person can play against the computer on the same screen.
When a second device turns up
Nothing is lost when a friend arrives with another phone: start a table on both instead and the same game spreads across the two screens, as in the 2 player games on different phones, each player with a whole screen of their own. Everything stays free and in the browser, with no account.
And when someone has to leave, the one who stays can keep playing on their own device: Snake, Whack-a-Mole and Tilt Run have solo modes, and the board games have a bot that takes the other side.
Questions
Is pass and play the same as hotseat?
Yes, both mean players taking turns on one device; here Chess, Checkers and Islands play that way.
Can four people share one tablet?
Yes, in Snake and Whack-a-Mole: a joystick or a zone each, up to four.
Can two people play at the same time on one phone?
Yes, in Air Hockey, Hot Potato, Snake and Whack-a-Mole each player has their own part of the screen, and in Tilt Run two people hold one tilt.
Can I play alone?
Yes, Snake, Whack-a-Mole and Tilt Run have one-player modes, and every game here except Spillover can seat a bot against you.