izigame.me

Kingdom Rush Frontiers is is basically a more polished version of the first game. It's still solid with a variety of fun levels and towers to work with. There's all new abilities and heroes, making the game feel fresh even if you've played the first game for numerous hours. The art style feels a little more refined with more detail on the towers, heroes, and environment, with the usual Kingdom Rush Easter eggs sprinkled throughout the levels for you to find. Just like the first game each level has several difficulties and challenge modes for extra challenge/stars. For anyone who has played the game for free in the past, this version feels noticeably harder, but still not too difficult. And lastly, your heroes remain leveled up, meaning once you power up a hero they remain at that level. This can make some earlier stages a breeze to complete challenge modes on.
This game has the in game shop from the mobile (?) version. You occasionally get gems as in game currency to buy items. I beat the whole campaign on veteran difficulty and all challenge modes without needing to use a single item. The game is noticeably more difficult but definitely doable without 'taking the easy way out' if you're worried about that sort of thing.
Unlike the first game, none of the levels feel overly punishing. Even the bonus levels, of which there are a few less than previous, only took a couple of retries to beat with a 3 star rating. There are also additional 'endless' levels, of which there are 2. These are nice bonus content that involve endless waves of seemingly random enemies broken up by a wave of elite enemies. It's a nice mode to play to try for a last few achievements, but feels a little cheap as the elite enemies really start to become 'impossible' enemies with the amount of health they eventually have.
Additionally there are multiplayer co-op levels, but I never touched them so I can't say what they are like.
The only complaints I really have are that some of the achievements are very grindy. One achievement involves stealing 10,000 gold with some of your soldiers. I knew I wanted to 100% the game from the beginning so I solely picked this unit as blockers and always upgraded pick pocketing to max immediately. I literally played through the entire campaign on normal and veteran mode, completed the heroic and iron challenges, and even completed some of the bonus stages, and STILL had to go back to another level (the one with the dwarves) to farm the last bit of gold. Several others also required a bit of grinding where you're more focused on choosing weaker upgrades for the achievement rather than the ideal ones for that particular tower. Not a huge issue, but can be a bit annoying at times.
Overall it's still a really solid game. It feels so similar to the first, but with small improvements here and there. I don't think anyone who enjoyed the first game will be disappointed with this one. There are minor complaints, but those will easily fall by the wayside thanks to how enjoyable the vast majority of the game is.