7 Wonders Duel (2): https://sevenee.mattle.online/welcome

Agricola (2-4): http://play-agricola.com/

Azul (2-4): https://azee.mattle.online/

Backgammon (1-2): 

Battleship (1-2): http://en.battleship-game.org/

Blokus (2-4): https://blokee.mattle.online/

Bingo: Coronavirus Edition (1): http://manfrancisco.com/coronabingo/

Board Game Online (1-16): https://www.boardgame-online.com/

Brass (2-4): http://brass.orderofthehammer.com/

Century: Spice Road (2-5): https://spicee.mattle.online/

Checkers (1-2): 

Codenames (4+): 

Decrypto (3-8): https://whoawhoa.github.io/decrypto/

Diplomacy (2-7): 

Dominion (2-6): https://dominion.games/

GO (1-2): 

Love Letter (2-4): https://netgames.io/games/love-letter/

Monopoly (2-4):  http://www.webopoly.org/https://www.pogo.com/games/monopoly

Neptune’s Pride: https://np.ironhelmet.com/#landing

Risk (2-6): 

Reversi: https://cardgames.io/reversi/

Scattergories (2-6): https://scattergoriesonline.net/

Settlers of Catan (2-4): 

Shadow Hunters (4-8): http://www.shadowhunters.live/

Solitaire (1): https://cardgames.io/solitaire/

Splendor (2-4): https://spendee.mattle.online/

Through the Ages: A Story of Civilization (2-4): http://boardgaming-online.com/

Yahtzee (1-2): https://cardgames.io/yahtzee/