I thank you for your kind words on the quality of the code in Alien. However, I had to sleep on your comment that Alien's depth isn't comparable to LOTR. (For the record, I own and love LOTR, it's probably #2 on my list of "games I'd want with me on a deserted island" ... I've always been a Tolkien fan, love the LOTR movies, and think the LOTR pin is beautifully executed, represents its theme well, and is great fun to play.)
I consider "depth" to reflect the number of distinct, meaningful rules in a game, and how they can interact with each other. Considering that...
LOTR has 6 very distinct main game modes + 1 mode mini-wiz (based on mode performance), with all modes exclusive. Alien has 8 very distinct main game modes + 2 mode mini-wiz (based on mode performance), with all modes exclusive, and with most modes boostable by out-of-mode activity.
LOTR has 4 very distinct primary multiballs, with 3 exclusive and 1 stackable. Alien has the same. On both games, multiballs can stack on an active mode.
LOTR has Gifts of the Elves; Alien has Weapons. Both of these can stack with other stuff as appropriate. LOTR does have SRFMB, which doesn't have an analog in Alien.
LOTR has Super features; Alien has a more accessible 2x Playfield. Both of these can stack with other stuff.
LOTR has [Super] Ring Frenzy; Alien has Rescue. Both of these can stack with other stuff.
LOTR has Destroy the Ring; Alien has nothing like that.
Both games have über wizard modes; LOTR's is for "winning" everything, while Alien's is for starting everything.
Both games have a nice variety of "miscellaneous" features.
Unless I'm forgetting something major from LOTR, I think Alien's depth is objectively right in line with LOTR's. However, I'd say that LOTR is "longer" than Alien, in the sense that LOTR requires you to do something over and over A LOT if you want to "beat the game". RotK MB alone requires 28 lit shots to "win" (the same 4 shots, 7 times over). That's certainly a LOT of shots, but I don't think that increases the depth of the game, it just makes it more of a grind. FotR MB requires "only" 18 lit shots to win, but if you don't manage that in a single go, it's really a grind to get back to FotR on typical game settings. I think this "length" is why Valinor is nigh unreachable for most players. Frankly, I wasn't interested in that level of exclusivity when designing Alien's rules... I think it's OK if a strong intermediate player "beats the game" once in awhile, and doesn't need an hour to do so.
This really isn't a competition -- I think players should play or buy a game because they love the game's experience, not just because it has the deepest ruleset ever created. But as I said, I went to bed last night with my brain percolating over Alien's depth, and just wanted to give a brain dump of my opinion.