Shadowrun Returns

This achievement is easily acquired during the flashback sequence at the start of the game.
Sam Watts will have access to a shotgun (the Benelli Raffaello). He's also very accurate with this shotgun and should have no issue landing every hit against any enemy that's 10 tiles away. Press the until this weapon is selected.
A "tile" is considered the single, square, space that your character occupies. When you're choosing where to position your character, this will show up as a white 1x1 square. Movement is based on "zones" and how many Action Points you have in a single round. You'll notice a white outline encompassing many tiles and moving to any tile in this white outline will only cost 1 AP. Moving outside that white line will show more outlined areas that will cost 2 AP to move to. Since Sam has 2 AP per turn, he can move up to two zones away in one turn, but will be unable to attack if he moves that far away.

(I'm putting spoiler warnings for a certain character, but it's not significant to the over arching plot of the game. The character is immediately revealed to you at the end of the dialogue section. I want to be sensitive to anyone who may consider that a spoiler, however.)

Start by picking a target and count as many tiles as you can away from them. You want to be on the 10th (or further) tile that you can occupy. When counting, consider your target to be at tile "Zero", the first tile you can move to would be "One", the second tile you can move to would be "Two", and so on.
Any target will do, but or the rifle wielding Renraku Security Guard will likely be your best bets. In my experience the security guard with the pistol tends to move around the most out of the three, but you may experience different movement patterns.
Once you've found the furthest tile you can move to, choose that, and then end your turn with the button. Continue moving and repositioning yourself until you are at least 10 tiles away. Once you are, you may begin attacking.
If you choose to attack he will likely go down within a couple hits of Sam's "Single Shot" attack, especially since Sam will be able to attack twice in one turn. It may be worth using his "Kneecap" ability since it will temporarily remove 1 AP from your target, which is good for preventing your enemy from moving too far away from you. The downside is that "Kneecap" can only be used once every 2 turns and deals less damage.