It's a tough call. Both are great games. Dead Space 2's gameplay is much more refined but it tries to disturb you more with gore instead of tension. Dead Space 1, however, has a greater sense of urgency and thrives on your paranoia. Some gameplay is in need of tweaking in Dead Space 1 (like lack of ammo) but most of these issues are fixed in Dead Space 2. I don't find either game incredibly scary but both games can occasionally get the jump on you. I would lean more toward the first game but you should definitely play both. Hope this helps.