This can be the first achievement you unlock in the game. Once you are introduced to creating clones in the prologue, you can simply spawn a clone by pressing
+
. Once you spawn your clone in, press
+
again to take control of your clone. Now crawl under the gate but do not complete the objective. Instead, run on over to the guard at the end of the room and let him kill you. You should be able to spawn another clone now, so just repeat this process until you get the achievement. I'm not sure if you can spawn clones infinitely anywhere else. Here, you can. Please watch my video if you are confused by anything. I also show you how to get the achievement for spawning 30 clones which is simpler to get.