What are these movies?
Alien Raiders is a terribly-named movie, though I can kind of see what they're going for: a bunch of criminals takes over a supermarket and holds the people there hostage--because (twist!) they are trying to protect all of us from alien invasion. So the raiders are both the aliens doing the invading and the humans trying to raid the aliens. Cue waa-waa horn.
A Film With Me In It is a super-dark Irish comedy about two affable schlubs--a failed actor whose brother is locked-in, whose girlfriend is growing apart, whose landlord is mean, whose apartment is falling apart; and a drunk screenwriter who never writes--who then have to deal with an escalating farce of death. The deaths are ridiculous, but the real comedy here is in how these two guys try to deal with everything, which is so god-damn hard for them. (At every single moment: so when Dylan Moran--the drunk screenwriter--introduces himself at an AA meeting, he does so in the most awkward way possible.)
The good, the bad, the replicable
Alien Raiders has many characters--the raiders, the hostages, the cops--which kind of splits the attention and drains our identification with most of the characters. So, say, when something terrible happens to character X, it's easy to say, "oh well, what's character Y up to?" At the same time, many of those characters are given some interesting thing to work with.
It's also so perfectly self-contained--just in and around this one supermarket. Not only does that heighten some of the danger and suspense, it also probably does wonders in cutting down cost. Which they could then spend on bloody special effects and squibs, since the film sort of boils down to regular joes vs. aliens.
A Film With Me In It has a similarly constricted location/scope, mostly taking place in and around this one house. And, similarly, most of the special effects budget probably went into fake blood. But the characters are so well-defined through just one or two scenes--the actor failing to make an impression at an audition, the drunk writer making the wrong impression at an AA meeting--that we don't need to see much of their lives outside of this house to understand who they are. And once we have their characters outlined, almost every thing they do is hilarious since they keep being put into tense situations.
The only negative thing I have to say about A Film With Me In It is a warning about the dog in the film, who does die. For some reason, people dying in Looney Toons fashion is amusing, but when it happens to a dog, it seems less so.