GP	AR	UV	Overall
4	5	1	5

Review by Colin Phipps

Regular readers will know that I have a preference for Doom 1 levels, so it was inevitable that I would get around to Retro sooner or later. CH Retro is an episode made to match the style of the original Knee-Deep. To be more precise, the levels adopt the style of that most favoured of Doom levels, Computer Station (Doom E1M7), an industrial style with a mixture of nukage lakes and computer rooms, with lots of windows between areas, large rooms overlooked by ledges and windows, and plenty of traps and secrets. The style is matched very well, with plenty of attention to detail with inset computer panels, external windows, and player corpses and the like for decoration.

After the first couple of levels, I was a little worried by the direction the episode was taking. There is a certain class of levels, particularly common among older Doom 1 levels, which specialise in replicating areas, or at least bits of areas, from Knee-Deep and joining them together into a "new" level. These sort of levels put the player in more danger of having their Knee-Deep trivia skills tested than of surprising the player with an original idea. Fortunately while the first couple of levels of Retro are definitely a deja vu trip, the levels quickly move on and get more serious with some very nice new areas.

Difficulty is something of a drawback with many Knee-Deep clones, and it's no exception here. Retro sticks to the plot and avoids using cacodemons or lost souls, or barons before the final level, and the monsters are rarely in large numbers. The difficulty is on average no more than the original Computer Station, which is fairly tame for experienced players. The interesting layouts, in particular lots of caged monsters and windows between areas, do keep the action from getting dull, and there are plenty of traps (although often showing on the map). The levels are all quite tight for health, as there are only a few stimpacks and a supply of blue bottles to keep you going, but these are augmented by a large number of secrets which include a few supercharges. There is a puzzle aspect though, with a minor maze at one level, and a number of hit-a-switch-and-run puzzles to be figured out to complete the levels.

Comments on each level, then:

1. First Contact — A nice little start map, rather like a smaller version of the original with the player working his way around some buildings around a yard. There are lots of architectural references to the original, with the tall windows in the start room looking out into the yard, and the annex holding a green armour. The opposition are about the same as in the original but in a smaller level, so they put up a fair fight for a brief warm-up.
2. Computers and Electronics — This map draws a lot of features from the original Nuclear Plant, including the dual winding stairways up to the first keycard and the computer maze, but also uses some more varied Knee-Deep features including a raised passage looking down over the start area as in Computer Station (Doom E1M7). The level is very cleverly connected up, with lots of windows between areas and opportunities to see ahead in the level. Just one easily spotted trap IIRC, so most of the difficulty comes from the low supply of health and the number of sergeants wandering around.
3. Main-Frame — Although containing a number of references to the original Toxin Refinery, this is a much more original level, with a large and impressive start area with a number of cages and overlooking ledges to make for a good opening fight. The trickiest part of the level is around the computer area (presumably the mainframe of the name) where the large number of sergeants, and a good little trap when you get the keycard, make for some fun moments. There's still a limited supply of health, but ammo is plentiful and if you get some of the many secrets then there's a supercharge available too.
4. Command Center — A nice little nukage base level, mostly set in rooms and ledges overlooking a couple of acid ponds. This one isn't modelled on any particular original Knee-Deep level I think, it's more a mixture of styles from Computer Center and Deimos Labs (Doom E1M7 and E2M4 respectively). Lots of windows over the main areas, and a number of little traps, keep the player busy throughout.
5. Chemical Processing Plant — There is a definite step up in difficulty at this level, right from the start, which is rather exposed with imps and sergeants looking down on the player, and there are some nasty tricks in this area. Once inside the base, the main part of the level is once again set in the rooms and ledges overlooking a nukage lake; there are some sizeable outdoor parts to the level as well, a combination not unlike Central Processing (Doom E1M6), and there is also a maze-like area which is similar to the one at that level. This level has rather more substantial traps and puzzles than those before it, and there's still plenty of enemies using the windows between areas to snipe at the player in between the big fights.
6. Primary Base — The nukage base theme continues; this is a fairly compact level with a network of small rooms and yards and passages, with lots of cages and windows between areas. The level progression can be a bit tricky, as there are a number of passages crossing at different levels to mix you up, and some switch actuated doors which can make it tricky to get around. There's also one door which is marked as a red key door but is in fact yellow, although it doesn't affect the level. There are some good fights against caged monsters where the player has to keep an eye on several targets at once.
7. Laboratories — One of the problems with a Knee-Deep style level is that the monsters are all quite weak. Two ways around that are to cramp the player for space, and use a lot of traps, and this map does both. Everything is on a very small scale, with very small corridors and no really big rooms - there are much fewer windows between areas, instead the level contains a lot of small passages, and the level progression is quite complex as the player has to find the right passageway to get through to new parts of the level and hit switches to make progress. The level progression is quite complex, and there are a few puzzles involving running between switches to get access to the way ahead; the way forward is usually not obvious but nor are any of the puzzles too taxing, and the author kindly opens convenient routes around the level once you have gained access to a new area. There are lots of traps, a mixture of hidden alcoves popping open when the player isn't looking, and lots of teleporting monsters appearing behind the player. It makes this probably the most dangerous level of the episode, so you have to play with a lot of caution as there is still limited health available.
8. Old Habits... — A fairly brief final level, with a clever hexagram built into the structure. A slightly tricky trap and a shotdown with 4 barons to finish off the episode.

Briefly then, CH Retro is a pleasant outing in Knee-Deep nostalgia. The original Knee-Deep style is captured well and the architecture is top notch. It's not going to give you any late nights struggling to complete it (unless you get stuck on the puzzles), but there is plenty of action; it's never dull, and E1M5 and E1M7 are particularly full of action. And that is more than enough recommendation for me.