Basically any modern AAA game. Most games released now are easier and more accessible.
A low effort high reward game would be like Rocket League and Counterstrike. The concept is simple, you have basic objectives but the skill required to get ranks needs training and perseverance. Any scrub can jump in and get Silver but to get to gold, elite and global you need a strong team or skilled players who know what they are doing and be consistent.
I would say the Souls games if you are talking SP you going high reward. It takes time to master but the concept is simple. WoW is another good one, easy to pick up and play but PvP and endgame requires you to use your brain (and skills).
Filled in one critical thing that was missing