Alien Breed
Like many other european gamers in the 90's, I owned an Amiga. Several ones to be exact, including my beloved Amiga 2000 and the much more modern AGA-equipped Amiga 1200. One of the premier game developers of the time was Team 17, makers of Full Contact, Body Blows or Worms. They are also known for a game series named Alien Breed.
It's basically a top down shooter where you control a single soldier who has to fight hordes of aliens. Imagine Gauntlet set in the Aliens universe with a difficulty that matches late 80's video games.
Alien Breed was followed up by my favorite in the Series - Alien Breed II: The Horror Continues - and Alien Breed: Tower Assault. After that, they would make two 3D games which were revolutionary on the Amiga.
In 2010, a new trilogy was released on Steam, Playstation Network and XBox Live Arcade. The new game is good, but it just wasn't the same Alien Breed feel for me.
To my delight, Team 17 has released the original 1991 Alien Breed on the Playstation Store, which includes PS Vita and PS3 Cross-Buy and Cross-Play. It contains Alien Breed, the '92 Special Edition and a few new level packs. It's playable with the original graphics or with enhanced visuals which look like Tower Assault AGA.
I like how they did controls, it's basically a twin stick shooter scheme: The left stick moves the character while the right stick shoots in the given direction. That's not that different than the Amiga version in that you usually shoot where you look, but it makes walking backwards while shooting more natural.
It's $9.99 and as said, that includes both the PS Vita and PS3 version.
Confusingly, there is also a $3.99 version for Playstation Mobile. From what I've seen it's the same game, but only runs on the PS Vita and some PSM-compatible Android phones. It also features a cash store and no trophies - it's $6 cheaper though and feels the same, so if you just want a quick fix every one in a while, that's an option.
For the sake of completeness, GOG sells the MS-DOS Version of Alien Breed and Tower Assault. Alien Breed II wasn't ported to DOS, and generally these versions aren't as good as the Amiga versions (which you could play on an emulator).