Intrusion 2 is a product of a different age, and partially should be judged according to that. And partially based on current age, as I played it now, and you'll buy it now.
The game is a huge zero in terms of story, people kept mentioning chapter names in the forums, but I haven't even got a single title, spoken or written word in the whole playthrough. Also the game has the weird mix of creepy-cool mechanic enemies, 3 different mechs that you can even drive for a bit, rideable giant wolf and kickass bossfights. It's well made nonsense, but that stems from the game series' origins.

The original, first Intrusion was released online on Kongregate, on Newgrounds, and on other sites - in 2008. Intrusion 2 is far from being a carbon-copy of the first, but it's very similar in lot of aspects - gameplay, character, climbing mechanics, general look and setting, and some huge bosses.

What is new, is a gorgeously made world, with greatly detailed sprites and enemy design, varied type of enemies and some bonkers physics and "AI" for some enemies.
The "AI" really matters in some cases, as uniquely made enemies move around almost in an underwater style and catch you with their tentacles, or weird 3-legged bone-robot-skeleton-cat things jump and wriggle around… it has some solid, otherworldly feeling to it.

I also mentioned the physics - it's both good, and bad. You can push around rocks to squish enemy soldiers, but for this the price is tripping over in every possible body and item in the word. Having to shoot cases that blocked the door so you can progress, eating a handful of attacks because a destroyed robot's arm blocks you movement. Jumping and bouncing works in a weird way that item shape, and I think velocity together decides how and when can you jump. Which can result either 5m long, or 3-4 meter high jumps. Or just a little springy walk that barely lifts you because you weren't connected to the ground properly beforehand. Which can be debilitating, as one bossfight involves jumping on rocks floating in lava, later levels grappling mechas use the clutter, that is blocking you, as a weapon and it's a real pain. So in short, while the physics system is quite well done, it's great when the stakes are low, while annoying and risky other situations.

It was an okay game - it reminded me of Plazma Burst, and while the boss design was hands-down amazing here, the core game could have used a little more meat on its bones.
It's repetitive and limited. The player has 5 weapons, of which 2 slightly different machineguns, 1 pistol that won't get used, a railgun and a slow granade launcher.
There is a great, over the top and fun ragdoll effect in the game, and it's so hard to properly trigger. A good, powerful shotgun or some similar weapon would have been a great variety. Also, if it could be possible, the harpoon mecha's harpoon would be exceptional for a different game mode - grabbing enemies and throwing them away, or killing them by smashing shipping containers to them is a joy with this phyics engine, and we got so, sooo little of it.

Music - it's super repetitive and uninteresting for the bigger part. I'm fairly sure that something went wrong on the penultimate level as music is 3-4 times louder than game sounds. On the other hand, the second boss' music was outstanding, and worked really well with the mechanics, which made it the most enjoyable bossfight of the game.

Overall it's a solid OK game of I guess a single person? who likely wanted to make a proper version/sequel to their game, and they absolutely nailed it. I think this game is a 6 or 7 our of 10, well above average - epending on your enjoyment and how it aligns up with your expectations. Not really higher, but because - I think - this game doesn't want to be more than fun, and that is perfectly okay.