2. Diablo III: Reaper Of Souls
A certain number one spot on this list is a title that ingratiates loot-based reward systems into its gameplay, but even that would be nowhere without titles like Diablo leading the way first. Whilst game theorists break down how the core idea of rewarding players in a sporadic fashion is actually more addictive than getting things in a constant stream - "Oh I didn't get something? Just one more go..." - Diablo's expansion re-release is a strong contender for why gorging on additional trinkets and miniature stat-bonuses can be far more enjoyable. Reaper of Souls takes the age-old gameplay pioneered by the likes of Baldurs Gate and polishes it up to a mirror sheen. Thwacking all and sundry never felt so good, especially when Blizzard added on an entire new Adventure mode that unlocks after the end of the campaign - something that'll eat up entire evenings and weekends if you let it. Alongside that are a myriad of smaller tweaks to the rewards system itself, removing the auction house and making for far more chances that you'll happen upon one of those luscious legendary drops right when you least expect it. Playable in as big or small a chunk as you can allow, Diablo is simple-yet-addictive gaming perfected, and although it's major PR push was back when it first launched back in 2012, this slightly under-the-radar gem is very much worth every second you can devote to it.