This mod will start were the original Half Life2 episode 2 ended, with the death of Alyx her father. She became sick by the loss and layes in bed. Magnusson needs Gordon to look for Kleiner, because he has disapeared. The last time he did see Kleiner was when he spoke about going to the Borealis to blow the ship and everything inside up. Gordon needs to travel by airplane to the North pole and find Kleiner, and save the ship. Will you be on time? And will you find out what the secret cargo is that is inside the ship?
Some levels have good variety of shapes, sizes, layouts. Others seem to be author's older work, because they are simple and monotonous locations using textures from Doom3 that look ugly because only diffuse was taken, normal and specular were not. Only parts where Doom3 textures look nice are complex doors, yet custom texture would still look better than a ripoff from other game. Later there will be phillipk textures which look out of place in Half-Life 2 mod. Corridors and rooms from some futuristic transport (seems like it's spaceship Enterprise, because that's what the manual in Breen's room says) also look out of place in Borealis.
Sounds and locking doors are used to hint where to go and prevent wandering in search for ways to advance in wrong places. Later powerup that shows solutions to puzzles will be appearing. Considering the length of the mod, it's really good to see that the author values the player's time.
It looks great at some parts: outskirts of City 18, airport and part of the city near it have spectacular views. Snowy city at the north has very detailed cityscapes with complicated layouts, and out of place Doom3 textures are minimal. Last levels where Gordon returns home look nice too. Mines at the beginning and snowy landscapes with buildings around Borealis looked decent - nothing made me stop and enjoy the scenery but overall design is good.
The research labs that remind of Black Mesa and rooms with rockets and engine test hit the right spot, creating a feel of Half-Life series returning to its roots, further reinforced by recoloring wall mounted medkits and chargers into HL1 colors.
Cutscenes are clever and imaginative, making the most out of existing animations, and when there are no animations, ragdolls are put to use. Some of them received a touch that makes them look even more professional - the camera animation starts right where the player is.
The resistance base we visit before City 18 looks weird - it seems identical to the one from Episode 2, even same room where we launched the rocket, but it's not in the forest, it's in some town instead.
Scary sounds of locked doors are a nice touch. I also liked headcrabs that crawl around like Doom3's imps and combine equipment which play animations when the player approaches. And the scene where Freeman looks up and sees several fast headcrabs on the ceiling.
Moving the car around broken bridge and unmoveable broken cars were pretty nice puzzles, though I don't know if they appeared in the mod intentionally or accidentally.
I liked the moment where you fall through floor that breaks under your weight, then after some time return there and see that someone put wooden planks there. It makes you feel that you're not the only sapient being around and everyone else are not AI controlled robots.
Teleporters that leave craters on the ground are awesome, and the effect when Gordon enters one of them looks cool, too.
Combat includes some interesting situations. Car that falls in the cave and obstructs the path gives the player a nice idea of crushing antlions with it. Walking around huge turret through the trenches, roof after highway of map29 which required clever use of cover, carrying the turret around because you have no weapons.
Ending is very rewarding. The radio host provides long awaited bits of plot, but he mentions help that came from Vortigaunts. I didn't hear the explanation of why they attacked Freeman.
Overall, some parts of the mod are great, some decent, others are mediocre filler that makes you want to quickly run through it. If only the same amount of time was spent on making few great levels that fit the game and don't look out of place, implemneting some cool new gameplay mechanics, then it would be an amazing mod that lives up to expectations it creates by its name Half-Life 2: Episode Three.