I found at least 8 nodes in the first two chapters. They're everywhere, and some very well hidden-- There are boxes that don't light up and nodes are usually hidden there. I would use the nodes on the ripper. This weapon is very useful in the game compared to the plasma cutter. In the console version, it would be the other way around.. The duration of an upgraded ripper can destroy three necromorhs easily (pregnant necromorph is simple as well). Aim for the legs and then walk back slowly and strike the head-- quick and easy you can also destroy the brute with the alternate shot (vertically), in four to six shots with precision and stasis.
I'd only say, spend on ammo first. Don't necessarily max out your ammo, but make sure you have enough to get you through until you might have the chance to buy again - better to have too much ammo, than too little. You'll get enough nodes throughout the game to upgrade about 3 items completely, and there's always New Game+ to upgrade the rest, so there's not much point in trying to upgrade everything on your first run through - better to finish the game than run out of ammo.
There's nothing that you have to do behind locked doors. Normally lock doors just have bonus things such as more nodes and money behind them.
I usually sell all my ammo whenever I find a shop... Melee makes this game so easy I don't see the point in even using those weapons. I just focus on fully upgrading stasis and the suit and then I take so little damage and have such high HP that I usually just let the exploding necromorphs hit me. It saves me the bother of actually attacking them.
By the end of Chapter three you could have had 8 nodes if you'd found them all. Don't know if that makes you want to start over, but certainly search around more.
The last tram section is the start of level 11 I think. When I got there I had full ammo for three of my four weapons--like 55 shots for the plasma cutter--and I hadn't really been buying any ammo. I'd spent my money on the suits and nodes so that I had the 3rd level suit fully upgraded, the plasma cutter fully upgraded, the stasis pack mostly upgraded, and 76 thousand saved toward the fourth suit. Having just finished the game, I have to take even more exception to the TA review--I didn't find that the game got too difficult at all, nor did I find ammo scarce, even toward the end. I never once died on any of the brutes that the TA review complained about, and in fact didn't die once in the last five or so levels (I think I only died three times over the course of the whole game). The TA review complained about the final levels being overwhelming based on the number of enemies, but I didn't see that at all. I also thought there was plenty of ammo provided throughout the game as long as you planned your shots. The difficulty was about perfect to me--just enough to keep the game tense, but the game was still definitely beatable.
*spoilers* Please help I am in Chapter 12, looking the Reactor core or something of a really big machine, I can jump from platform to platform shaking the ipod, but i dont know what to do ????
When you enter the room, you think you need to go to the far side of the room as with other low gravity areas. Instead, you're basically going to move to the bottom of the reactor. So look over the edge of the platform (or any of the other 3 platforms you can immediately see), and you'll see MORE platforms along the walls heading down the side. Aim until your target goes green, then shake to jump. I actually ended up jumping to the base of the reactor in like 2-3 jumps, cause I looked around and happened to find the lowest platform possible.
You have to make your way to the bottom of the reactor. You'll notice that not all the platforms you can jump to are on the same level. Start jumping to different levels. You'll quickly come to a lip/ledge that you need to jump over. At that point the platforms have big elevation changes and you'll quickly reach a platform at the bottom. After that, jump down from that platform to the reactor floor and then . . . I loved this game. Best game in the app store. Best combat in an iPhone or iPad app. Best level design, best gameplay, most polish, fullest, most immersive experience . . . I could go on and on. Definitely worth the cost (which is why I bought both the iPad and iPhone version). Edit: of course I got distracted while answering and see see my answer is now redundant since I took so long to post
