I may have found a way to get into the basement from an LBLJ. If I could get through the key door would the area be loaded?

Yes, the Area will load if you go through the Door, but you obviously need the key for it since you cant enter keydoors without an actual Key, because the area will be unloaded if you dont use the key

The basement is loaded even without a key. Upstairs is the only place that isn't loaded without a key.

actually, not true. using a blj anywhere cheat. or carefully using tas to blj into the door, you'll see that it's not loaded. even if you clip behind it and enter the door from behind, you won't be able to enter the door because the (you need a key to unlock this door) message appears. so no. not possible.

To my elementary knowledge, it isn't that the basement is loaded without a key, but rather that you can enter through the moat door which doesn't require a key (but requires TAS-only PU routing to enter with the water undrained). Entering any key door requires the key to use that entry. If there was no moat door, with everything else unchanged, then 1 key would be impossible.

The 30 star door and the level behind would still be loaded though right? If it is then what if you could generate enough speed to get past the key door, and into the 30 star door

because no. nothing through the door is loaded. it's just a black void.

@Apianbelle then how is the 1 Key TAS possible?

@CheesyLeech because it enters through the moat door providing an alternate method of entry into the basement. The key itself isn't the magic, it's just that the key is necessary to enter basement without PU movement.

Let me put it in other words: There is 1 way to load upstairs: get the key and enter through the upstairs door. There are 2 ways to load basement: get the key and enter basement door, or enter through the moat. The TAS enters through the moat, but this is not RTA viable. The only alternative to load the basement is using the key.