I am playing a non lethal play through and I like to explore ever nook and cranny.
At first I upgraded Hacking to lvl 2. Then strength to pick up heavy objects. Then a bit more hacking (lvl 3 and stealth). Parachute and Wall breaking next. Finally I upgraded hacking to lvl 5.
Don't take jumping, those places can be reached by rearranging objects.
Same gun can be upgraded multiple times.
Make sure you get those sweet Praxis kits at the LIMB clinics.
Same here plus going for the no alarm and playing on give me Deus Ex difficulty. I actually only upgraded hacking to an extent and going invisible. I always seem to have >5 paraxis kits in my inventory all the time and throughout my entire playthrough i probably only used a weapon <20 times. The freedom on how you want to approach each level is really cool. The game is really easy, if you are patient. The only thing i hate is that friggin shanghai map, and the exclusion of a map on the main screen. It really has me excited, since this was a success, on the next entry to the series. There is somthing here that isnt at that highest level but it has a foundation to build and improve, ala Assasins Creed.