What are the chances of getting a highly sought-after random reward from a virtual goodie bag in an Apple App Store mobile game?
A check of 10 games by The Straits Times showed that it can be lower than 1 per cent, with one popular game citing a chance of 0.00005 per cent (see table).
Some observers are concerned because they contend that many of these goodie bags, also called loot boxes, have addictive gambling-like qualities and can be bought or opened with real cash, or virtual currency bought with hard cash.
Game developers were forced to reveal the odds of getting loot box prizes in games from the App Store after iPhone maker Apple made it a requirement last December.
Many developers have complied. Several revealed the odds earlier due to a similar requirement in China in March last year.
How the odds are disclosed varies. Some games reveal the odds of individual rewards, while some show the chance of winning an item from a category of rewards.
For instance, popular multiplayer online battle arena game Vainglory cites a 0.00005 per cent chance to win one million Ice, which is a premium currency in the game.
But in Clash Royale, which has collectable card game elements, the chance of getting a card from a category of cards dubbed "legendary" is 0.19 per cent. The odds for specific legendary cards are not shown.
Rare rewards can give players a big advantage in some games, while in others, they are just for show.
The odds in some games can change. In role-playing game Mobius Final Fantasy, there are special events that raise a supreme card's odds by 10 times to 0.8 per cent.
Even so, these odds - except Vainglory's - are higher than the 0.0002 per cent chance of getting a royal flush in the poker card game.
Apple's move follows an outcry late last year by gamers over the gambling-like features of the loot boxes in shooter game Star Wars Battlefront II, which prompted investigations in countries such as Belgium, France and the Netherlands.
Google was unable to confirm that similar measures as the ones Apple made would be implemented for the Google Play mobile store.
Mr Jonathan Kok, a partner at RHT LawTaylor Wessing who practices law in media and entertainment, said there are no reports of Apple ending a game maker's participation for not disclosing the odds.
But he said that if Apple discovers a violation, it will likely notify the developer of the breach and require the developer to address the breach within 30 days. If it does not, Mr Kok said Apple would remove the offending app from the App Store.
Revealing loot box numbers is useful, said Mr Shawn Toh, chief executive of local game developer BattleBrew Productions. "This makes it clear for players to decide if they want to take the chance and get what they want, provided that the odds are fair, of course," he said.
Other experts were uncertain that revealing loot box odds would help. Dr Thomas Lee, consultant psychiatrist and medical director of Resilienz Singapore, said: "Gambling operators - like in horse racing or Toto - also advise patrons on the odds of winning. But some of these patrons still find themselves addicted to gambling, even when they know that the odds are stacked against them.
"These odds help you to make a better decision, but it is up to the individual to decide whether he wants to take that chance. Unfortunately for some, they end up addicted."
Mr Allan Simonsen, chairman of the International Game Developers Association for Singapore, said some users are susceptible to a "feel good" high from getting loot box rewards, adding: "They're not going to be looking at a probability table to decide whether they want to open the box or not."
• Additional reporting by Isabelle Liew