Okay, first you obviously need a good topic. Online gaming is probably NOT going to work b/c you don't want to seem like a gaming addict. I think the idea about using tech to help the world is actually decent; make sure you provide specific ex. of how tech can aid society so that it doesn't seem too generic or cliche. Make the essay like 500-700 words (no longer or else you may bore the admissions officers). Also, don't try to be overly pedantic and use hard words capriciously b/c then it sounds too fake; just try to use a conversational/casual, but also gramatically-correct, tone. For other essay ideas, you could try influential person, travel experience, academic classes you've enjoyed-I know they're a little cliche but it's nearly impossible to come up with an "original" essay these days.