Can't cast a vote... (Mainly because I suggest 2 of them... --- a.) Dice and Roulette b.) Playing Cards)
if you've been playing cards at home just for fun and you want to switch with an online game, then I really suggest to stick with the game whom you know best/ familiar. With this, you can eventually win a game with the help of your own experience. As for the other one, which is the Dice, I simply suggest them because they only come into two option whenever you play them. so it's really easy to understand how it works. Though the only thing you should consider is where to play this kind of games.

Example: 1.) Finding a platform where they give 50-50 in terms of winning/losing. etc.

Indeed, but foremost gamblers they already know how to play poker before going online, so they should just stick with playing cards.