This was actually a surprisingly good adventure game. Not great, but good enough to recommend for fans of Myst style adventure games. This review covers both parts in the series, because although the first game is nowhere near as good as the second, I feel that they are still probably best played one after the other for the story if nothing else.
Firstly, a point of warning - the second game had all sorts of graphical glitches on my GeForce Go 7900 GS making it unplayable. I ended up streaming it from my Mac Air which played it with no problems. I couldn't find any other reports of the issue I was running into - in fact, most people seemed to indicate that they could run the second game fine, but had issues with the first (which worked fine for me), so YMMV.
I picked up both in the series from a recent Indie Gala bundle and after finishing the first one I considdered it to be a fairly average adventure game with forgettable characters, a lack of any meaningful story and a pretty lame ending - but I still had a fairly good time with it, and it was short enough that it didn't overstay it's welcome. Fortunately, the second part redeemed it as the story picked up and the characters instantly felt like they had a lot more depth.
You play as Mina who was trying to set a new world record, but wound up shipwrecked on the shore of a Mysterious Island. Your phone's battery is dead and you can't contact anyone. You want to know the story of the first game? That's pretty much it. You get to explore and see some of the sights described in Jules Verne's novel "The Mysterious Island" trying to find a way to recharge your phone and bring down the shield that surrounds the island, but since I have not actually read the novel I can't comment on how much is a reference to it and how much is new.
In your adventure you find an adorable monkey you adopt and name Jep. In the first game Jep basically becomes a tool to reach high objects, but in the second game you actually spend a good part of the game playing as Jep, since he can go places that Mina can't and can talk to other Monkeys on the island to make friends... and some enemies.
Graphics wise they remind me a lot of the Myst series - particularly Myst III as they use the same technique of fully pre-rendering the scenes from every position you can stand in (and in the second game from two perspectives since you can visit each location as Jep who is much shorter than Mina) and allowing you to freely rotate the camera in any direction. That was a nice trick used at the time to give the game stunning graphics (by the standards of the day) without having to render it all in real-time.
Like most adventure games you find plenty of things to pick up, but here it actually feels a bit over done - both games even give you multiple tabs of inventory (around 8 or so) to organise it because there is just so much stuff. Items can be combined in the inventory to produce new items or tools, and many of those tools can be broken apart again to recover the items used to construct them, which is often necessary to do (particularly in the first game), as the components often need to be used again elsewhere, whereas most of the constructed tools only have a single one-off use.
The first game has much more emphasis on combining items than the second - to the point where working out what items go together actually forms the vast majority it's puzzles. While the combinations do tend to make sense (and there are notes on the more complex combinations), the sheer number of items you find can make it hard to keep track of everything to work out what might go together - it was so overwhelming I often ended up just doing a whole bunch of trial and error to see what could be combined as the resulting tool might give me a clue as to what I might use it with. Eventually you get access to an encyclopedia to provide hints on the items, but by the point you manage to do that you have are near the end and have already solved the hardest combination in the game to get the encyclopedia.
The second game does a lot better in this regard - there is far less emphasis on combining objects and when objects do need to be combined the descriptions often provide clues or the recipe will be in a notebook you find fairly early in the game. Because of this, I didn't really find the need to waste time trying different combinations, and attempting trial and error didn't have much success anyway.
One redeeming factor of the first game - and something I actually quite liked, was that there are almost always multiple solutions to each problem (and you get bonus points for any progress towards the alternate solutions). In some cases you needed to collect a bunch food and the extra solution was simply that there was way more food than you needed if you looked hard enough, but in other cases there were two different items you could constuct to achieve some goal - like two types of batteries that could be constructed out of completely different materials (I still have no idea where the silver was for the other type), or at least three types of projectile weapons. I didn't see this as much in the second game - there's still an excess of food, but I didn't see any obvious alternative solutions to puzzles like the first.
Interestingly, the first game had some conditions where you could destroy an item, and it's the first game I've played where I was concerned that I might accidentally waste or destroy an important item that would prevent me from winning the game later on. I'm not certain if that is possible or not - especially considdering all the alternative solutions. The thing is - one item that can be destroyed is the knife blade, which was the single most used item in the game - I'm a bit curious to replay it at some point and see if there are enough alternative solutions to still win if you destroy the knife at the start of the game... The second game actively seemed to prevent you from wasting inventory items you might need later ("I could use that to start a fire! But, it would be a shame to burn the xxx"), so I was never worried about losing anything important in it.
Besides item puzzles, the first game has a bunch of nearly identical code puzzles and a guess the item quiz - and that's about it. The second game has a lot more variation to it's puzzles (yay, only one code puzzle this time), though I did have to resort to a walkthrough once or twice when I couldn't quite work out what I was supposed to do (usually because I was overcomplicating things, like the puzzle where you pretty clearly need to use trigonometry since you're given elevations at certain points and the distances between them - only it turns out that the angles are all 0 degrees which completely eliminates the math and makes the distances irrelevant... overthinking it...) - I noticed that some of the puzzles had an "easy" mode which you could use at the cost of "pride points", but the puzzles I got stuck on didn't have that option, so I never tried it.
In both games I did often find myself walking around with no real idea of what I was supposed to be doing - the second game was a bit better in that regards as it had objectives, but the objectives still tended to be vague goals rather than specific things that needed to be done. I did feel that the games could have done a slightly better job of dropping hints (Maybe instead of "I think I forgot something" it could have said "The grindstone isn't secure"). The first game was small enough that I never had to resort to a walkthrough (I almost did at one point, but just as I was about to give up and hit shift+tab my mouse finally passed over the saltpeter I was looking for), but I admit that I did have to use a walkthrough a couple of times in the second.
Overall, a good adventure game that I'd recommend to Myst fans. Maybe wait for a sale though.