Cryptark

This is a hidden gem in the limited time free games. This sci-fi action game actually has more strategic elements than actions. The key to success is to make good plans. You can pause the game anytime and take your time to think. So the game pace can be either fast or slow, up to you.
While the default difficulty is quite challenging, all achievements can be obtained in easy mode and not hard to 100%.
The overall experience is very good on steam deck.

This is a really enjoyable roguelike space game, reminded me of Heat Signature a little bit. The gameplay loop is rather simple: you need to enter the spaceship and destroy its core to complete a mission. As difficulty increases, so does the randomly generated spaceships' size and complexity - more and more systems are added that sometimes create quite a puzzle to solve, namely which systems to take out in which order and which route to take.
There is a decent variety of weapons and enemies, and two main game modes: Campaign (with a time/money pressure for each mission) and Rogue (no time and money, but your weapon loadout, ammo and health persist through each mission). There is also a Coop Campaign mode, but since I didn't play it, I'm not sure what it's worth. Rogue Excavation is just a single and somewhat quick mission that most likely serves as the game plot wrap up.
Took me a little more than 10 hours to 100% this one and to be honest, I can't say that the learning curve is THAT bad (saw plenty of "OMG this game is so hard" comments and reviews). The shield is probably the first thing you'll need to be aware of (save your HP), then energy weapons (endless ammo, but need recharging), then melee weapons (deal with anything but larger targets), then everything else.
However, either accidentally or on purpose, the dev team made the second mecha suit unlockable just for 2 artifacts - Rook - broken in the worst way possible. So if you are looking for a challenge, make sure to skip it and pick another mecha suit first. If you just want to complete missions and pew pew everything, Rook is the way to go. Its built-in special ability makes you completely invulnerable to anything; elite units, mines, nuclear explosions, swarms, alarm lasers, literally anything can be tanked straight with your face. You can't move or shoot while shielded, yes, but that's hardly an issue with a bit of timing: shoot - shield - shoot - shield - move - shoot, and so on.
Can easily recommend Cryptark for a certain number of evenings. Also, the OST is sick - try googling this: d1-3B Rigilkent z8-8q!

If you're a fan of roguelike shooters that reward careful planning as much as quick reflexes, CRYPTARK delivers in full. Every mission challenges you to customize your mech loadout, study enemy ship layouts, and disable key systems with precision. The mix of tactical decision-making and fast-paced twin-stick combat is deeply satisfying, and each procedurally generated derelict offers new threats, layouts, and strategies to master.
Visually, the game stands out with its gritty, biomechanical art style and explosive visual effects. The sound design is equally impressive, weapon impacts feel powerful, the soundtrack builds tension perfectly, and the voice acting gives real character to your crew. With its high replay value, engaging gameplay loop, and immersive audiovisual design, CRYPTARK is a hidden gem that deserves a place in any roguelike fan’s library.

A great combination of Gothic Cyberpunk style, fast action, strategy, and dashes of comedy. Different playing modes and mobile suits give a very different playing experience, and the music is rad and appropriate to the creepy, borged out enemy.

CRYPTARK is one of the games I picked up while cleaning the "trash" catalogue in my Steam library. That catalogue is for games I didn't mean to play, for different reasons. Whilst I couldn't be bothered to review most of the ones I (begrudgingly) decided to play - as to clean my games library - CRYPTARK is, in fact, good! Plus, considering that I've got it for free, even greater. Fun game loop, well thought out game design, pretty polished. Recommended!

Not bad of a game, fun, very challenging, and Jerma.....

And a tip use keyboard and mouse for some reason controller pov when scouting is smaller compare to left shift on a keyboard and mouse.

Interesting! Cryptark is a 2D side-scroll action shooter with heavy strategy elements. You have to gear correctly (Battletech) and choose which systems you want to target (Shadow of Mordor). It's frustrating, but once you get the hang of it, it's really quite a fun game, more importantly, it makes your objectives clear and doesn't make you grind too much get 100% completion. It's not just a good game, it's thoughtfully designed.