9 hours ago, Scouting Ninja said:
Adding in one or two adverts doesn't help much, for the most part things stay the same.
As mentioned in another post, it does let you sell a no-ads IAP 
It also depends on how/when you show them. A common trend now seems to be opt-in fullscreen video ads, either on a timer in the main menu (e.g. Once per hour to get a prize) or after each level/death/etc (to get a bonus, extra life, etc). Once-per-day bonuses also seem to be a common strategy often a with a phone notification reminding players to open the game and get their bonus (a nudge to help retention).
These choices won't be arbitrary or devised in advance perfectly for most successful games though. It's common to soft-launch in one territory only and then do lots of A/B testing (use science to find out which variations get best results). New Zealand seems to be a common target as the small population means you don't waste a lot of opportunity, but they still have similar tastes/habits to North America (assuming that's your real target market -- a NZ soft launch won't help you tune the strategy for China). The "AAA Mobile" studios that make millions per month likely have a lot of people full time on looking at analytics and devising experiments... At any scale you at least want to know why/when people are quitting your game, and whether people are opting in to your bonuses or not. Things like offering a bonus life at the start vs end of a level, or even just the color of a button could potentially be the thing that makes a feature work!
To get ARPU up though, besides optimizing your ad usage so that people are happy to see a lot of them, you need IAP. Your ARPU for just the IAP-engaged segment can be several dollars, which gets dragged down to a tens of cents average by the freeloaders.
Loot boxes seem to be the current fad - play the game and watch ads to get coins, spend them on boxes, get prizes... Then directly sell coins/boxes/prizes too.
As posted above, the most successful games will be very scummy... However I love Crossy Road as an example of a less scummy option - the gameplay is just endless frogger an exist in full out of the box. Collecting coins in black game, opting in to videos, once-per-day bonuses and IAP let you get loot boxes, which give you re-skins of the artwork - no effect on gameplay, but made a huge amount (for an indie dev). It is a little scummy to people who feel the compulsion to unlock everything in that you can't buy prizes directly, just gacha boxes... Flappy bird also just had banner ads on death with no 'scummyness' but made a huge amount (for an indie dev) simply off volume of players.
