The Weight of Command
Most games tell you that your choices matter, but Mass Effect actually makes you feel it. When this released in 2007, it changed the landscape of the RPG by making the 'dialogue wheel' as important as the rifle. You aren't just playing through a script; you are Shepard.
What makes this special for a family setting—provided the kid is old enough for the M-rated content—is the 'Water Cooler' effect. You’ll find yourself asking, 'Wait, you saved the Council? I let them die so I could focus on the Reaper!' It sparks genuine debate about leadership.
The Age Factor
The ESRB 'M' rating is mostly there for the romance subplots and the violence, but it’s the intellectual weight that really sets the floor at 13. A younger kid might enjoy the 'pew-pew' of the space combat, but they’ll likely get bored by the hours of political maneuvering and technical lore-dumping at the Citadel.
Original vs. Legendary
If you're looking at the 2007 original, be warned: it hasn't aged gracefully in the graphics or UI department. The Mako (the planetary rover) is famously difficult to drive, and the inventory system is a mess of spreadsheets. The Legendary Edition released in 2021 is the definitive way to play this. It keeps the 2007 soul but fixes the 2007 headaches.