[Fanatical] SteamWorld Heist (93% off | 0,98€ - Historical Low)

if you like the base game, then yes. It gives you a new robot and a couple of unique weapons to find. It is on sale too.

It's a traditional RPG style party system, so the DLC is completely optional.

Gear's a basic +1 stat kind of deal, so that's not a consideration, either. The new character does play a bit differently, though, which I felt made it worth its price. I recall it being on the strong side, though, so beware that it might make the game feel a bit easier. I think the pack also gives a few more cosmetics (ie, hats, which normally you obtain by shooting them off of enemies wearing them). I think there might also be a small number of short missions tied into finding/developing the new character? I recall they make for a pretty interesting addition on the game's setting, as well, despite not being especially deep (since you get a unique perspective on some things due to the special nature of the DLC character).

Ultimately, it's both completely unnecessary from a more critical perspective but, at the same time, still a decent deal for $5 retail (75% off during Steam sales, same as it currently is on Fanatical, but you should be able to use OMEN10 for 10% off with Fanatical [Note: Remember to use this on the base game as well!] or, if that's expired, buy the base game and use the 5% coupon you get from that on the DLC).

Further, since it IS content that doesn't have a large impact on the game, that means you can always just swap the character back out if you feel it's too strong or doesn't mesh, and still get a few little additions to the game, so from that perspective, it's definitely a DLC that's worth trying if you like the base game.

I wouldn't get too far into the game though, when testing it out without the DLC, if you're planning on getting it, since I believe the gear drops get added directly to the game through a random loot table, so you'd probably be missing out on chances at those. Don't recall if the DLC character scales its level to your party or not (it's been ages since I played the game last, so I don't even recall the leveling system itself well, now), so that'd be another concern.

It does- iirc- take a few missions for the initial mission to obtain the DLC character even shows up, though, and you can always backtrack to the missions once they show, so it's not like you'd have to restart a campaign (no matter how far you've gotten into it) once you get the character.

Heist's a fun, tactical RPG-lite physics game. It does however fall short a bit due to having a bit of a weak endgame, due mostly to the simple game systems getting a bit tired, and no real new gameplay mechanics ever being added in. Outsider adds a bit more variety, and therefore keeps the game feeling fresh longer. From that perspective, it's quite recommendable.

TL;DR version: Yes.