Battlefield 2 vs Diep.io
Battlefield 2
Battlefield 2 is one of the Battlefield classics and rightly so. The game lets you play as a soldier in one of the three major military superpowers: the United States, the Chinese or the newly-formed Middle East Coalition. Players will have access to a wide range of weaponry to do battle with as well as a variety of vehicles. Similar to the original game, the game has a large-scale multiplayer mode - the hallmark of any game from the main Battlefield series - that can accomodate up to 64 players on a single map.With more weapons and vehicles for you to play with, Battlefield 2 is a pretty nice sequel to the Battlefield franchise. However, considering that it has not yet been reworked, unlike the first Battlefield, and that currently, there is no way you can purchase the game unless you get the hard copy off eBay or a similar site, you might be better off buying any of the other Battlefield games.
Diep.io
Diep.io is a fun tank-like IO game where players play as pencil-drawn tanks on a piece of white (and sometimes gridded) paper filled with other hostile tanks as well as a variety of obstacles and Polygons. Shooting at Polygons and other players will earn you points to level up your tank to the next tier, unlocking a wide range of upgrades (or "classes" as the game calls them). At frequent intervals, AI-controlled bosses will be spawned allowing players to work somewhat cooperatively to earn a ton of experience points.Many players are calling out Diep.io as being a clone of the previously popular Tank.io (not sure what happened to Tank.io though), but considering that it's currently the last game standing, I guess it's safe to say that new players will never know about Tank.io but will instead be able to enjoy its legacy through Diep.io.