What I might add real quick is take note of who wins at what game. There are strong points to each game and generally kids will be better at some than others. If you can make your lesson plans with that in mind it helps.
I also try to have one team game in every lesson. That means that everyone will lose or win together as a team, at least once in the lesson. The idea is to build up team work and they almost always win together
They occasional lose, so it doesn't seem like I'm always giving it away.
If you can play a variety of games that lead to different winners every time then you'll see kid start to understand that "sometimes you win and sometimes you lose, the fun is just playing the game." They may sulk and that's OK. I hate to lose, too. Just let them be and as long as they try again next time, don't worry about it.
It also helps to have some games that are pure luck and are independant from skill, knowledge or English ability, bingo for example. That gives everyone a shot .
I hope that helps.