I am presuming you do not want two monitors? You have indicated that your brother says you need those specs? The only component you have mentioned is a i5 CPU ans a graphics card as you play the odd game. It would help if you mentioned what the odd game is as it will certainly have a bearing on the graphics card.
Microsoft Lumia 950 vs Lumia 950 XL: What's the difference between Lumia 950 & 950 XL?