Several questions:

1- Obstacle cards are only revealed when explored?

2- Are the other cards underneath an obstacle card revealed when the obstacle card is revealed or only after the Obstacle has been resolved, example: cards under the Power Failure Card.

3- If the Power Failure card puzzle is not solved, in the next turn does the Investigator have to spend an action to attempt to solve the puzzle or is no action spent when trying to solve puzzles?

4-Fall of the House Lynch: Does Event Card 1 give (2) Horrors if doing 3B and Clue 3 has not been found.

Thanks

Guy Sajer GD said:

1. Yes, except in Lost in Time and Space map from Forbidden Alchemy expansion, as the eras in time indicated underneath the Obstacles must remain in mystery for the investigators.

2. The obstacle must be resolved first. Those cards are not revealed until the obstacle has been successfully passed and it says to discard. For example, if a puzzle must be completed, only when the puzzle is completed may the card be discarded (if that's what the lock or obstacle card states) and the next card on the stack be revealed. Sometimes a room may be locked AND have an obstacle underneath the lock card. If this happens, first the lock must be passed (as a move action), which is flipped over and you resolve its rules text. Any cards underneath the lock, including an obstacle card, remain face down until explored as an action. Next, if the investigator successfully passed and discarded the lock card, as an action (if available) the investigator may explore, revealing the obstacle card but any other cards underneath are kept face down until all obstacles are resolved.

3. Yes, the investigator may next round spend another action to explore and try solving the puzzle again. Remember to leave the puzzle as is when the player may fail to solve it with his allotted puzzle actions; only reset the puzzle if told to do so by a Mythos card or some other game text (alchemy puzzles from Forbidden Alchemy is the exception to this however). Also heed that Joe Diamond's Magnifying Glass does not allow him to attempt the same obstacle puzzle twice, nor would an investigator continuing to move repeatedly on the same turn against a lock puzzle work either; each investigator is only allowed one try for each respective puzzle a turn. For example, an investigator may attempt an obstacle puzzle in his room, then fail doing a lock puzzle against an adjacent room, to then use for his final move an attempt against a different lock puzzle from a different adjacent room (i.e. action, move, move).

4. Not sure. Do not have card in front of me. Hope I helped with rest though.

 2- So what you are saying is that after you "solve" an obstacle with an exploration action, you have to explore again to see the cards that were under the Obstacle.  Correct?

No, if you solve the Obstacle, you get the cards under it with the same Explore.

That's right: interacting with an Obstacle card at all requires an Explore action (except, of course, when taking an axe to it). If you fail the puzzle, then clearly you have to Explore again later. If you solve the puzzle, you keep right on exploring down the stack.