Choose Fission Superstar X
Choose Fission Superstar X if it's Steam Deck Verified, so handheld play works out of the box. Fission Superstar X launched in 2019.
Fission Superstar X vs Space Mercenary Defense Force
Fission Superstar X and Space Mercenary Defense Force both land in Action, Indie, RPG on Steam, which is why they keep getting compared. The comparison below is built from each game's Steam metadata — release year, genres, categories, Steam Deck status, price, and review score — refreshed daily by imho.run's scraper. Headline differences: Both share Action, Indie, RPG on Steam. Fission Superstar X (2019) is 4 years older than Space Mercenary Defense Force (2023). Fission Superstar X is Deck Verified on Steam Deck; Space Mercenary Defense Force has no Deck rating yet. No login or purchase needed — scroll for the full table, the verdict FAQ, and links to ranked similar games for both titles.
Which should you pick?
Choose Space Mercenary Defense Force
Choose Space Mercenary Defense Force if you want a Casual experience. On Steam, it's the newer release (2023) and ships with the modern feature baseline. Space Mercenary Defense Force launched in 2023.
Both Fission Superstar X and Space Mercenary Defense Force sit in Action, Indie, and RPG on Steam, so either pick lands in the same broad neighborhood. Use the side-by-side table for the feature view, or follow the "Games like" links below to see ranked alternatives for either title.
Side-by-side comparison
 Fission Superstar X |  Space Mercenary Defense Force | |
|---|---|---|
| Released | 2019 | 2023 |
| Genres | Action, Indie, RPG | Action, Indie, RPG, Casual |
| Platforms | Windows | Windows, Linux |
| Steam Deck | Deck Verified | Unrated |
| Price | Price unknown | 4.99 USD |
| Steam reviews | 83.7% positive (104 reviews) | 9 reviews |
| Multiplayer | Single-player only | Single-player only |
| Developers | Turbo Pelvis 3000 inc. | Tom Paradise |
Side by side
- Both share Action, Indie, RPG on Steam.
- Fission Superstar X (2019) is 4 years older than Space Mercenary Defense Force (2023).
- Fission Superstar X is Deck Verified on Steam Deck; Space Mercenary Defense Force has no Deck rating yet.
Fission Superstar X vs Space Mercenary Defense Force — FAQ
- Should I play Fission Superstar X or Space Mercenary Defense Force first?
- If you want chronology, Fission Superstar X (2019) came out before Space Mercenary Defense Force (2023). If neither is a sequel to the other, order doesn't really matter — start with whichever fits your current mood, since both share enough on Steam to make either a reasonable opener.
- Are Fission Superstar X and Space Mercenary Defense Force similar?
- They overlap on Action, Indie, RPG on Steam, so the catalogue groups them together — but "similar" depends on the specific mechanics. Use the genre + category rows above to decide whether the overlap matches what drew you to the one you've already played.
- Does Fission Superstar X run on Steam Deck?
- Yes — Fission Superstar X is rated Deck Verified by Valve. Space Mercenary Defense Force doesn't have a Deck rating yet, so its Deck behaviour is currently unverified.