All secrets present in Serious Sam HD: The First Encounter with quick links for each level below:

00:00 Intro
00:13 Hatshepsut
01:46 Sand Canyon
03:07 Tomb of Ramses III
04:38 Valley of the Kings
05:34 Moon Mountains
06:55 Oasis
07:46 Dunes
09:38 Suburbs
11:07 Sewers
12:17 Metropolis
12:31 Alley of the Sphinxes
12:46 Karnak
15:35 Luxor
17:36 Sacred Yards
20:22 The Great Pyramid