A locked door is one of the oldest puzzles in IF, and is of great use to the game designer; it allows them to restrict an area to the player for a while, slowing down the exploration of the game-world and giving the player concrete rewards for solving puzzles. Unfortunately, they tend to have only one solution that will enable the player to get them open, and many a forehead has been bashed against one in despair.
- OPEN x (WITH y)
- UNLOCK x (WITH y)
- PICK x (WITH y)
- PRY x (WITH y)
- KNOCK (ON) x
- ENTER x
- LOOK THROUGH x
- USE x ON y
Don't Waste Your Effort
- First of all, make absolutely sure that the author actually intends you to unlock the door. Sometimes an author will just use locked doors as a way of making an area seem larger without having to implement more rooms. This is particularly likely if there are a great many doors (e.g. a hallway in a hotel) or if the door is not heavily implemented or distinctively described.
- Never ignore the possibility that you just can't open that door yet. This is particularly likely if there are other obvious puzzles you haven't dealt with, or other areas you haven't explored yet; sometimes a door will only open from the other side.
All Locked Doors
- Scrutinise text for pointers. A good author may have hidden a clue away somewhere in a description.
- The Famous Five approach: scout around for a hidden button, catch or trigger that opens the door. (Yes, usually these are for secret doors, but you might well have found a secret door but not know how to open it).
- Rely on the goodwill of NPCS (or at least their stupidity).
- Be polite and KNOCK - particularly if you have reason to believe that you're expected, and you're not snooping arround illicitly.
- If there are wandering NPCs, try tailgating; if they can get through a door that you can't, just follow them through.
- NPCs might have the key (or passcard, or authorisation codes...) Wangle it out of them by persuasion or theft; this is a chapter in its own right.
- Are there hinges mentioned? Those are a weak point. Unscrew them, explode them, dissolve them with acid...
- Pull the door off. Tie the handle (or any other likely points) to a vehicle, moving parts of machinery, a horse, a precariously balanced boulder... then start it up.
- Sometimes, very rarely, violence is the answer. ATTACK the door, maybe WITH something. Put an explosive device through the letterbox. Desperation can pay off.
Doors that Just Won't Open
Sometimes you'll come upon a door (or equivalent) with no apparent unlocking mechanism, which nonetheless won't open.
- Is it a door with a conventional key that's just underimplemented? Unkind authors might not have implemented a separate lock object, or even bothered to describe it on the door. The giveaway is usually an 'It's locked.' message when you try to open the door.
- It may be that this door will never be openable. Carefully read descriptions of the door, particularly what happens when you try to open it. If there's a thousand tonnes of rubble on the other side, or it's a room you have no business going into, you may never get in.
- It's fairly likely that this door won't open from this side, and you'll have to find another way in or get an NPC to open the door.
- Some door-equivalents - usually trapdoors, manholes, ventilation grilles, and the like - require a crowbar or something of the sort to get open. You could try this with jammed doors too.
- If a door is described as rusted, it's very likely that the hinges will need oiling.
Doors With Conventional Locks
- Nine times out of ten, the solution is to find the right key. Try every key you've got (although if the author was polite, this shouldn't be necessary). Otherwise you'll just have to keep searching.
- Look through the keyhole, if you can. This may produce clues, or it may be the sole purpose of an unlockable door.
- Locks can sometimes be picked. Either you'll need a specific lockpick item, or something thin and pliable; a hatpin or a piece of wire, for instance. These may work like normal keys (UNLOCK x WITH lockpick), have their own verb (PICK lock WITH lockpick), or employ the most generic term possible (USE lockpick ON lock).
- Rusted locks can need oiling too.
- The oldest lateral-thinking solution in the book: there's a key in the lock, but it's on the other side of the door. The solution to this is almost always to slip a piece of paper (or equivalent) under the door, then push the key through with a long, thin item (letter-opener is traditional), so that the key falls onto the paper and can be retrieved.
- A tiny handful of extremely sadistic authors have sometimes required you to PUT the key in the lock and then TURN it. If this is the only solution, you may want to reconsider why you're playing this game.
- Have a gun? Shoot the lock. (Unlikely to work in real life unless you're using a shotgun, but this is IF).
Chained, Barred, Padlocked
- A padlock can be treated with most of the strategies applied to a conventional lock; see above.
- Chains can be broken, usually with heavy-duty tools (bolt-cutters, pick-axe) but also with less conventional means (acid, explosives).
- Chains are a good point of attachment for the yank-the-door-off strategy (see above).
- An interior bar (or latch) can sometimes be lifted with the aid of a jemmy: something firm and thin that you can slip between the door and the jamb.
- Boarded-up doors might be unboarded with the use of a pry-bar or axe.
- It may well be that the chains and boards are the author's way of telling you that this door's never going to open.
Electronic Locking Doors
- Once again, you may just need the right key. Often this will be a swipecard (too many IF authors have been traumatised by those things in university computer labs). It may just work like a normal UNLOCK key, but a less considerate author may make you SWIPE CARD, PUT CARD IN SLOT or similar.
- Look for a way to screw with the electronics. Some electronic doors will automatically open if you merely switch off mains power. Conversely, some need mains power to be restored before they'll open. For more subtle approaches, look around for nearby control panels and the like which might gainfully be opened up, exposing wires to tinker about with.
- Some electronic doors will want to take biometric readings. If you have reason to believe that you're already authorised, it may just be a matter of TOUCHing or LOOKING INTO things. More likely you'll need to cheat the scanners by means of identity theft. Photographs or scans of authorised personnel might just work, or you may need to find an authorised person (or corpse) and remove body parts, blood, or DNA from them. (IF protagonists aren't sociopaths, they're just... uniquely motivated.)
- Locked Door at TV Tropes Wiki.