However, one solicitor told the BBC that the practice became "legally grey" once micro-transactions were involved.
"If you go into a baker's to buy a bun and they give you the wrong change and you walk away knowing you have been given more change than you handed over in the first place, that's theft," Sara Ludlam, an intellectual property expert at Lupton, Fawcett, Lee & Priestley told the BBC.
"So, arguably if you go into this game knowing you are supposed to be paying for these weapons and you notice a glitch allows you to accumulate them without paying, that's theft as well.
"But it is arguable because it's a new area."