Spartan Survivors is free with the experience and quality of at least $5, which I would pay; $10 would be on the expensive side.
The game is easily understood in the first hour of playing, consistent throughout, almost bug-free (as far as I can see), and fun and satisfying to play.
From the start, there are ten characters to choose from, and each one has a different starting weapon. Most of them use weapons that are otherwise available as XP rewards, but can be more effective on that character as it can be aimed manually. Some characters do have their own exclusive weapons, such as Sergeant Johnson with the Battle Rifle, and "Agoat" with the Magnum. However, in my opinion, it feels odd for the Magnum to be an exclusive weapon for a character with no iconic history, if any. But that may just be my own bias.
Each in-game experience reward has its own use with only moderate overlap. At full upgrades, the Rocket Launcher, Fuel Rod Cannon, and Plasma Mines have quite a bit of overlap (almost full-circle, fixed-range explosives), but that's not necessarily a bad thing. Vertical upgrades are just as important as horizontal.
As far as positives go, that's as specific as I can be right now. There's more to it than that, but I'm currently unable to articulate it. For the negatives, there's nothing big. Again, it's a free game, but there are just a couple things to be desired.
The first objective issue is a single actual bug that I noticed. If I've observed it properly, the bug only occurs between the Bathrobe skill and the Speed Boost drop. Bathrobe, as it describes, appears to increase all stats, including movement speed. Naturally, using a Speed Boost at any level of Bathrobe further increases both of their effects. However, with Bathrobe, the massive increase in speed sticks around long after the Speed Boost effect ends, at least according to the screen effects that indicate the boost. I don't know if it's actually "stuck," or if Bathrobe silently extends the duration of the Speed Boost. If it is stuck, then a patch would be good, as you'll often run faster than your projectiles and ram into enemies. Although, if it is a natural extended duration as a result of Bathrobe, then adjusting the visuals of Speed Boost and the description of Bathrobe would alleviate any confusion. All in all, it has not been an actual issue, just awkward. The bug(?) does eventually fade. Sometimes it feels like it stops when I level up again, and other times it doesn't. Not sure.
Another negative (maybe) is not a bug, perhaps a simple mistake, or just a little harmless developer bias; the Sniper Rifle uniquely has two purple levels. Every weapon's upgrade looks like this: Blue (to start), then Green, Purple, Orange, and finally Red. The Sniper Rifle has two Purple levels. The first is a 50% increase to damage; the second is increasing bullets fired by +2. The sniper is extremely powerful as an auto-targeting weapon even if you remove either of those. It IS fine as-is. It's not a problem, in my opinion. It is ONLY a player advantage. But I thought I'd mention it.
First real negative, a bug: The "Luck" skill doesn't seem to do anything. At max upgrade, it provides 50% more XP and XP drop chance, according to its description. I have played MANY times with and without this skill, and no matter what, it does not push the player level past 40-43, depending on the level. If you chance 5 Lucks in a row at levels 2 to 6, then from level 6 and onward, you are gaining 50% more XP from basically the beginning. I welcome any corrections to my estimate, but on maps that get you to exactly level 40, an additional 50% XP at the start SHOULD get the player to at least level 55 by the end. Those are just my observations.
The second negative, the MUSIC. Man, it's a good thing Bathrobe (the developer) chose a cover of Covenant Dance as the main repeated soundtrack. That's probably my favorite one from Halo: CE. It's an easy listen and a dynamic track. But eventually, repetition WILL beat the dynamic out of any song. Covenant Dance is the soundtrack for almost every level except for two. Even for a first playthrough, just hearing it for the second level in a row causes one to raise their eyebrows.
And finally, the worst negative: The game is still interactable when out of focus. If you are using one monitor, you will be subject to this problem straight away. Even right now, as I type this review and click around it, I can hear the game confirming selections when my mouse is in the right spot. Multiple times, both during the construction of this review and doing other things, I have ended up unpausing the game, changed character, gone into the settings, and so on, all without having Spartan Survivors even VISIBLE on my monitor. This issue needs to be fixed ASAP, free game or not. I've been in a decent mood every time I've played this game, so this has yet to cause me frustration, but eventually it will, and it definitely has for other people. Please, this needs a fix!
ALL IN ALL, the game is good. It's VERY good for free, enough that I would advocate for the addition of a price tag (if the copyright allows and owners are not forced to pay after already owning the free version). I hope that Bathrobe or Aubega, whoever is responsible for it, is able to add more music, maybe using the original template (Brothers In Arms as the song for Pillar of Autumn and the Halo Theme for The Maw, just as a couple examples). But even if that is not changed, and as long as they get to that unfocused window issue, great game. It's a win for fans.
