In between levels, you can upgrade your weapons and fortress by visiting the Outpost. The Outpost is where you can trade your loot (which you pick up during your missions) for upgrades, including new weapon types, more squad units, and better fortresses with more battle positions. The first fortress only has three positions—you can equip three weapon types, but with multiple squad units of each of those types—while better fortresses have up to eight. The Outpost is where you can really start to strategize—each weapon type has different stats, including attack points, range, damage type (structural or creature), and pierce rating (for enemies wearing armor).
If you're a fan of tower defense games, you should definitely check out Roaming Fortress. It's a unique spin on the genre that plays out very well: it's got excellent graphics, a nice soundtrack, and it's plenty challenging. If you're not so big on tower defense, you may find the game a little frustrating past the first few levels—but it's still worth a look. The first map—which has 12 levels—is free; each additional map costs $2; or you can unlock all future maps, of which there will be at least five, for $5.
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