Escape from Skaarj Base is a great introduction to one of the gimmicks that ONP has, the gameplay is very easy to understand but defeating the level can be tricky, the ship behaves like the Redeemer from UT99 (even the Redeemer sound is used for the ship's engine

) the only difference is that you can decrease/increase the speed with the primary/secondary fire. You have plenty of room to maneuver (except for the final section) so it should be pretty easy to beat the level with a low speed, however if you are trying to beat the level as quick as possible or if you want to beat the Uber goal time, then good luck, but the map has some shortcuts you can use, the choice of path is the key to beat the Uber time.
The Betrayer's Path is when ONP really starts, you are thrown in a familiar looking place if you have played Unreal before and enemies are everywhere, this map introduces another one of ONP's gimmicks and that's the ally system, it's a great surprise when you met your first Nali only to see him wielding a Dispersion Pistol and then starts following and protecting you. The ally system is a great natural evolution of the gameplay of Unreal and also story wise, after the defeat of the Skaarj Queen the Nali must feel more confident and brave and therefore some Nali now start to rebel against the Skaarj, one unfortunate pawn that was never used was the ally Krall, it would have been cool to have a map where Krall and Nali were working together against the Skaarj. Another gimmick introduced in this map is that you can destroy barrels and crates by just touching them, the odd thing is that since you have a Dispersion Pistol with infinite charge you don't have to worry about ammo, so the new barrel/crate system feels redundant, it's still fun though. Gameplay is tight, while ONP is overall easy this level can be quite the challenge since there aren't that many health items, also this map has no secret pickups so you don't have a safety net. There are some interesting scripted sequences like the Krall ambush or the Brute killing the Nali and when the Skaarj uses a box to crush a Nali, poor Nali

. The level ends with a fight against an "Evil" Nali, the fight is basically you fighting one of those Nali allies introduced at the start of the level. That Nali behaves a little bit like a bot but thankfully without the speed and ferocity of a bot, so it isn't that difficult, however you have to be careful since sometimes the rockets start to follow you

, also there are other Skaarj during that fight depending on the difficulty so it would be better to start prioritizing.
The level geometry is really good in both maps, ONP has good quality control when it comes to level geometry and lighting (except for some "interesting" levels that appear later in the campaign). The choice of textures is great and the alignment is good for the most part (however there are some oddities, the worst alignment issue is the terrain textures). The terrain is awesome, mappers really learned how to make this types of brushes by this point, I bet that if ONP was made during 1998-1999 the terrain would have looked very, very different

. ONP has new textures and the one used in mountains is used all over the place, even the Nyleve Falls remake uses the new terrain textures instead of using the originals. This gives ONP an consistent look, so bonus points for that. Lighting is also well done, ONP was the pioneer when it came to using powerful lights in a specific place to create natural sun light shadows, after so many years it still looks great, but there are some places where the shadows look ugly but for the most part those shadows look fantastic. However the shadows aren't the only highlight of ONP's lighting : good use of colors and many dark corners to add to the atmosphere, another highlight is the skybox, great use of lights with different colors and use of textures, I also love that the green asteroid appears in the skybox because that asteroid plays a small part of the story latter, it reminds me of the Sunspire that appears in the skybox of the majority of the levels before it.
Also bonus points for the reflective look of water zones, they look pretty cool
Sound design is decent, The Betrayer's Path has many Ambient Sounds (but no Dynamic Sounds

) and the choice of sounds is very effective. Music is good as well, Escape from Skaarj Base doesn't use any music which was a great decision in order for players to focus completely on the new gameplay gimmick, The Betrayer's Path uses music from Unreal and they are used very well including music changes depending on what's going on. Neither of this maps use the new songs from ONP, but that's a good thing since the campaign is waiting for the right time to start playing the new music.
Issues I found :
Escape from Skaarj Base :
-Sometimes when you touch the ceiling of the map you get stuck.
-If you start the level pressing the primary/secondary fire you will start shooting your weapons.
-Texture alignment for the terrain is bad, the same goes for all maps in ONP.
-For some reason the sky in the final cutscene has dark textures instead of showing the skybox.
-The map has some actors that don't do anything because they were copy pasted from Demon Crater like Pathnodes, a Creature Factory and two Skaarj Troopers
-This level doesn't have a safety net if you play it online.
-There's a teleporter out of bounds.
-When you beat the Goal time or the Uber time you should get a reward with bonus point for your score....., this map doesn't reward you at all if you beat the Uber time
The Betrayer's Path :
-Many translator messages come from books, but those books can move. Rookie mistake

(You can also use this books to go higher up and skip sections of the level)
-The ally Nali have a tendency to get stuck on movers, houses and aren't clever when it comes to jumping down. The most challenging thing about this map is babysitting your Nali allies.
-This map (just like the majority of ONP maps) use invisible brushes to create the natural looking shadows, but only because they are invisible doesn't mean they don't have collision.
-The majority of the doors are TriggerControl, the problem is that if someone dies near the door the door will always remain open.
-A Nali fruit near the Brute is floating.
-There's an enforcer clip near the end of the map that gets destroyed by the door when you touch it.
-This level has many places where secrets could have been added, but instead this map has no secrets.
-There are some trees with wrong collision values.
-When you fall off the map there are triggers that kill you, however they only affect the player.
-Some translator messages have issues, the messages are incomplete. Thankfully Delacroix made a fix to restore the cut messages.
Somewhere in Nevada...