In Arkham Horror, one can get the Necronomicon from the Curiositie Shoppe, for $8. The game takes place in the '20s, so they didn't have nuclear weapons back then. The point of the game is for all players to cooperate and stop the Mythos threat, be it through sealed gates or through combat, so nobody is alone in battle. Some characters, like Sister Mary, cannot go insane, while others like Michael McGlen lose less Stamina than others.
Also, please bear in mind that this is based on Arkham Horror, and it is quite obvious that you have not played it. If you had, you would know that Cthulhu takes teamwork to pull down, and that items such as the Blue Watcher of the Pyramid can actually ward off an Ancient One's attack for a full turn. Others items, like the Elder Sign, will instantly seal a gate and impede the progress of the Ancient One's awakening by one gate.
As far as reading the Necronomicon is concerned...it is indeed in English, but it costs 3 Sanity to use. You can also get allies like Professor Mandrake, who reduces all Sanity losses by 1.
As for monsters? They are not hard to kill, it's their own attacks that are killers. For example, the Elder Thing has only a toughness of one, which means it only takes one successful hit to kill it. However, it has the Nightmarish effect, which causes the player whom it encounters to lose one Sanity before combat occurs. It also does three Stamina damage if you attack unsuccessfully. However, monsters are also avoidable, so it is optional to go into combat. If you successfully defeat a monster, you gain points that can get you Blessed when you have enough. Blessings make your attacks more likely to succeed.
Sanity losses do not effect the player any further than stopping certain events like gaining an Ally from happening if you do not have enough Sanity.
So, as you can see, I already have the concept thought out. Need I say more?