SteamWorld Tower Defense feels like a time capsule to a time long forgotten; drowned by the luxury that is everybody being able to make and upload a game to a storefront and everybody then being able to experience said game. Through the passage of time and evolution technology gamedev has become way easier than ever before, which is obviously a good thing, but it sometimes makes me forget that it wasn't always like this.
It is especially interesting to me as it is the first game in a series I'm very fond of.

Unfortunately this wasn't only the first game in the SteamWorld series, but also the first of many games by Thunderful (which were back then known as Image&Form),
while they were going through the transition from edutainment games to full on indie-development in the year of 2010, where it wasn't nearly as profitable as nowadays and therefore obviously suffers from some growing pains.

That said, if you have ever played any game by Thunderful you likely how talented their developers are. They often try their hands on a new genre of game and hit it out of the park on their first try and a lot of those qualities are already present here, especially in terms of their trademark humor and visual delivery, which are both stellar.

The game could be a fun enough tower defense game if it only weren't for the overly punishing difficulty. Now I am by no means somebody who has played a lot of this genre, but the difficulty has not only been a problem to me, but is a sentiment of a lot of different people (some even on this site) and is not helped by the lack of documentation on this game.
The only gameplay video I've been able to find on the internet is the twelve year old one uploaded by the official YouTube channel, which doesn't show a minute of actual gameplay and the trailer. This game is so obscure that even the wiki page is far from complete.
To beat the last few levels I had to visit this Twitter thread from 2015 which has been visited by (comparatively) many people over the years and has responses all the way to last year and while it is far form perfect, it was the best resource I could find.

All in all I can only recommend this game to one specific kind of human, which is basically me, who is really into SteamWorld games and videogame/-history, which is something I would have said about 2 months ago.

If you want to play this game nowadays, you can't, because it has now outlived both storefronts it has ever been available on, being the DSi- and e-Shop. I would really like this getting the Anthill/remaster treatment where it was not only made available on the Nintendo Switch, but also given some quality of live improvements, after it became harder to access.

But as it stands that probably won't happen. The SteamWorld series is currently undergoing a now 3.5 year long hiatus, there have been three+ projects in the series we have been aware of, only one of which ever got an official name and a trailer being SteamWorld Headhunter, which itself we haven't heard a word about since last year (late 2021). Furthermore Thunderful has recently showed their disinterest of currently making another SteamWorld game via Twitter.
Even if a SteamWorld game releases in the next few years, it probably isn't this one as the last significant mention was a Vinyl released commemorating this games 10th anniversary

So if you are interested in playing this game or any new SteamWorld game, the best thing you can probably do is wait, re/play the previous games and spread the message as menial of an audience as it may reach, just like I did by writing this review.