Building up a library for your Xbox One can be an expensive endeavor. There does exist avenues for cheap and free games as part of the XBL Gold/Game Pass Ultimate service, but these monthly fees also add up over time.

Thankfully, an increasing number of free-to-play software is populating the already crowded Xbox One store. It's true that many of these are a bit deceptive in their boasting of "free" content; revolving around microtransactions. Still, there are a growing number of titles which do prove fun and enduring without having to shell out for downloadable content.

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With this list, we'll cover 5 of the best free games currently on the Xbox One store, as well as 5 that just aren't worth your time.

10 Not Worth It: Roblox

Roblox (1)

Despite technically being free to access, Roblox largely hinges on a system of the cheekily named "Robux," a sort of in-game currency that must be purchased separately. This emphasis on microtransactions might be fine if this was actually a quality game. Instead, Roblox comes off as a cheap Minecraft knockoff - with far more shallow gameplay and even blockier graphics.

Roblox is more of a user-generated toolkit with Lego lookalikes rather than a standard game. Players can create their own games spanning a number of genres - everything from racers to shooters. Unfortunately, much of this user-made content is goofy, shallow, and cheap-feeling.

9 Worth Downloading: Path Of Exile

Sure, you might say Path of Exile doesn't quite hit the gold standard of the Diablo games when it comes to dungeon crawlers, but for a free-to-play romp, it's actually a lot of fun. You're bombarded with a slew of monsters, as you venture through a variety of in-depth dungeons, caverns, and other environments.

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This game's impressively rich considering it doesn't cost a penny; and is strengthened by cool mythological themes, satisfying upgrades/powers, a massive skill tree system, and tons of content. While it's on the grindy side, the hack 'n' slash gameplay is well-crafted and enjoyable.

8 Not Worth It: 3on3 FreeStyle

Remember those charming NBA Street games by EA Sports Big from the early 2000's? Yeah, 3on3 Freestyle essentially feels like a cheapened version of those.

The game centers mainly around online play - but look luck finding many others to play against on the Xbox One version. In the typical free-to-play model, 3on3 also entices you to spend money and in-game currency to decorate your cartoony characters with clothing and other flair. There are bouts of fun in these basketball face-offs, but most of the experience is bogged down by clunky mechanics, bland gameplay, and super annoying AI.

7 Worth Downloading: Warframe

warframe fans playing song in-game guitar

While this online co-op shooter/RPG can be a bit grindy, it keeps you on the edge of your seat with tons of thrilling action, fun upgrades, and enticing loot. The best part is, you can experience the bulk of its gameplay without spending a dime.

Being a fairly old release, Warframe has gone through a number of reworks, refinements, and additions, further adding to its quality. This game is absolutely brimming with content - with a seemingly endless palette of enjoyable weapons, engaging missions, and a cool sci-fi premise to boot.

6 Not Worth It: Battle Ages

As far as free-to-play RTS titles go, Battle Ages isn't a horrible game. But beyond its basic empire-building premise and competent mechanics lies a pretty derivative and dull experience. Also, while the core gameplay is free to access, Battle Ages leans on the aggravating "pay to win" model, which entices you to shell out for gems in order to have a real shot at making headway.

The gameplay somehow manages to be convoluted with its interface, while also feeling watered down with its lack of control for ground troops.

5 Worth Downloading: Fortnite

Hitting the gaming scene as perhaps the biggest sandbox phenomenon since Minecraft, Fortnite is a great option for a free-to-play experience that both enjoyable and deep; especially with friends.

Fortnite runs with the exciting "battle royale" conditions that made PUBG such a smash hit and improves on the formula by making it accessible with its limited survivalist gameplay. At the same time, the game is rich with its tactical approach, thanks to its in-depth building/mining mechanics and its vast, colorful stages. The combination of gun battles and fortress-building makes for a unique dynamic that's endlessly appealing.

4 Not Worth It: Fallout Shelter

It's odd that this glorified "clicker" bears the name "Fallout," given its limited, enclosed style clashing with the free, open-world sensibilities the Fallout RPGs are known for. Outside of the post-apocalyptic 50s theme and Vault Boy callbacks, there are few qualities here that feel even remotely like the mainline series.

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Another aspect that strays from the character of the franchise is its utterly limited, passive gameplay which lacks purpose or reward. It plays like a watered-down Sims knockoff, as you must oversee and manage your vault, which is populated with cartoonish Vault Boy lookalikes.

3 Worth Downloading: Killer Instinct

This flashy modern-day rendition of Rare's edgy fighter reigns as one of the better fighting experiences you'll find for the Xbox One - free or otherwise. The game isn't perfect, with its somewhat limited features and lack of characters. Yet, the solid mechanics, awesome fighters, and slew of unlockables help to fill this void.

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The gameplay balances simplicity with depth, as it rewards well-timed combos and counterpunches, while allowing you to hold your own with button-mashing madness. Despite being several years old, Killer Instinct still holds up with its sleek aesthetics, rocking soundtrack, and smooth, detailed animation.

2 Not Worth It: Powerstar Golf

Sometimes there's a good reason games are free. They may be vehicles to entice you to purchase supplemental content, or, in the case of Powerstar Golf, it might just be overly-simple and lazy.

The game uses a sort of basic version of the commonly-used timing meter, which determines the speed and accuracy of your ball. Outside of a somewhat detailed system of upgrades, the actual experience of this golf game is pretty bland and uninteresting. It lacks the depth or gloss of more refined golf sims, while failing to provide the charm of an arcade-style golf game like Mario Golf.

1 Worth Downloading: Apex Legends

Like some other entries on our list, the out-of-left-field FPS hit, Apex Legends, has had some months to grow more refined and more fleshed-out. Though it still has its curious quirks, this game now stands as one of the most enjoyable, well-crafted battle royale games out there.

Apex drops you into a vast, expansive world where you're left to fend for yourself - and 2 other teammates - utilizing an elaborate, intuitive system of pinging to streamline communication. The gameplay is akin to "Overwatch-meets-Call of Duty," as each Legend is unique and comes with their own neat abilities like zip lines and portals. The upcoming season 3 looks to add even more to the fray, adding a new rifle to the already vast arsenal, as well as a new Legend.

Next: The 10 Most Amazing Free Games On The Xbox One