Let's Play X-COM Enforcer Mission 5
In which we're on approach to The Worst Mission Of The Entire Game.
This mission is just fine, aside the impending, gut-clenching dread. It's a straightforward kill 'em all mission. The only particularly notable thing it does is introduce Chryssalids, and they're not very interesting in Enforcer. I like their model, don't get me wrong, but they're just a bizarrely big, durable melee enemy. We don't have to worry about them snacking on civilians to make more of themselves or anything like that. If I recall correctly, zombies never crop up at all, in fact.
I show off the Mass Driver some here. It's basically your classic Video Game Railgun: it fires projectiles that travel through and damage every enemy in its firing path. While it's not particularly obvious as yet (Because most enemies die in one shot to most attacks at this point), it also does good damage per shot, so it's actually a good weapon for basically any situation. Its upgrades are geared toward crowd control, adding explosions on impact with a wall and then adding explosions when hitting enemies. (I think these are de-facto improvements to its damage against individual targets as well, but it's difficult to keep track of this stuff in Enforcer's chaotic combat) It's a fun, solid weapon you should always unlock as soon as you reasonably can.
The Lazarus System upgrade is fairly unique and even more of a must-buy. Where normal powerups are on a timer, the Lazarus System lasts until you die, at which point it revives you. Upgrading it makes it so you also explode in the process, clearing the area of enemies, then an even bigger explosion, then also you get temporary invulnerability. You can only carry one Lazarus System at a time, but you can always pick up more after you've revived. This is a huge help as difficulty ramps up, or if you're just not very good at the game, or if you're playing on one of the higher difficulties.
The Bonus game is kind of creative but pretty eeeeh. Collect randomly-spawning Data Points and try not to die as the floor increasingly falls away into Pits Of Doom. If you do fall in, you don't get any of the Data Points you collected. I imagine it's normal in Bonus games to lose Data Points if you die, but most of the Bonus games are fairly difficult to die in so I'd have to manually test that to be sure.