All Hallows

It all boils down to this - the BONUS LEVEL - accessible only if you got all 59 secrets (or used the Cheat Code). Save your game after the final level then load up this final test of your endurance. Keep in mind - you start this level with no inventory and you MUST be at FULL HEALTH later on in the level, so be careful.

Start by climbing the metal ledges and make your way to the center structure. Do a running jump to the slope and get the Flares then jump to the center platform and monkey swing out over the cathedral ceiling and drop. CRASH! I told you you needed to be 100% healthy. Limp over to the Medkit on the landing and fix yourself up. Get the next batch of Flares from the purple platform then move to the walkway above the bookshelf.

A switch is in the alcove above the bookcase. Flip it then drop down to the floor and climb up and jump to the central structure then do a running jump and grab to the ledge and shimmy left to flip the next switch in the upper alcove. A hall should now be open back on the floor level.

Head down this hall and run across the floor as it falls out beneath/behind you and flip the switch at the end. Return to the main room via the monkey swing which takes you over the spikes below. Return to the bookcase and get on the ledge so you can monkey swing to the left. Drop and immediately grab so you can pull up to the small area at the other end of the monkey swing and climb above the cable-slide.
Get the Vault Key then take a ride down the slide. Make sure to drop off just as you slide into the light to land safely. Pull up onto the area above the pillar then drop and hang off the other side to spot an open door. Take the monkey swing across as you catch on fire then drop into the water ahead to put out the flames. Swim past the piston and push the button then grab the Medkit from the ledge to the right.

Above the ladder, do a quick roll and grab the edge to trigger (but not fall through) the trap door. Jump across the hole and head to the vault. Use the key to open it up and shoot out the grates before dropping into the water. When you finally surface you will find a guard dog and his master. Kill them and explore the final area. Head towards the items to end this secret level.