Hey there. Welcome to the forums. I'm a fellow new game designer / developer as well (from Baylor University, Waco, Texas). Glad you found your way here! Now then...

Remember these are athletes placed in an arena for all to see, so these games modes should be layered experiences with twists. Something like assault from halo was always an exciting game to be a part of for example.

Don't constrain your design options by requiring a "layered experience with twists" in the fashion of Halo's "Assault" game mode (I played the Halo Reach one).

1) Simpler rules make the gameplay easier to understand.
2) State-based transitions effectively mean you will have multiple games within one "game" (which is what the Assault mode was). This adds needless complexity.

3) Even games that don't appear to have them will contain layered and surprising gameplay. Take soccer for example. While the rules are simple, there are many levels of depth within the tactics people have in coordinating their team and in the skills players have to effectively manipulate the ball. There are also crazy twists that can occur when something unexpected happens during gameplay (those "wow" moments in traditional games).

So you don't need to forcibly create multiple layers or twists in order to get the gameplay you want. Any sport you make should naturally exhibit depth and surprise in its design.

One more thing, random weapons do drop on the map according to spawn timers.

Um...this really shouldn't be a "requirement" for your game (if you can help it). While it certainly could be viable for certain types of games, this is still a limiting factor in the types of effective game designs you can implement.

Now, if you come up with a design for gameplay where random weapon drops actually strengthens the gameplay, then go for it. But that is a design decision that should be made AFTER you've figured out what kind of gameplay you want to have, not before. Just tacking that "feature" onto your game design may in fact have a detrimental effect on your ability to devise enjoyable gameplay, esp. if it just doesn't "fit" the ideas you come up with.

So yeah guys if any of you can help me out with figuring this out, it would be greatly appreciated!

Okay, so your two main sources of inspiration should be...

1) successful shooter game modes

2) real sports

The successful game modes you mentioned work because people actually LIKE them, so you shouldn't consider them to just be these "suffocating" things. They work for a reason. Figure out what those reasons are, and then craft a new experience accomplishes the same thing.

1a. TDM, kill players on other team. Requires social coordination, precision gunplay. Have to survive. These 3 things result in mental gameplay and suspense which makes it fun.

1b. CTF. Grab object from enemy and return it. Requires coordinated actions involving distraction and/or blitzkrieg tactics. All about manipulating the attention of your enemies = more mental gameplay.

1c. FFA, TDM without the social coordination. Relies even more heavily on leveraging the level layout to ensure you aren't flanked unexpectedly. Anticipating where people might be. More mental gameplay.

1d. KOTH, More social coordination, but this time there are two options. If you don't have the Hill, you wanna use Blitzkrieg tactics to just completely annihilate everybody within the zone. You also have to be on the lookout for people on the edges trying to maintain a presence and bomb any of your guys who then move in to take over. If you DO have the hill, you want 1 person staying inside (to minimize the damage you take) and everyone else hiding in the vicinity to bomb/takeover in case the Hill-maintainer is killed. Either way, you are trying to anticipate when it is safe to enter the Hill and when it isn't, trying to anticipate where the other players are going to show up and when based on respawn times, etc.) More mental gameplay.

1e Oddball, team or not, this is a mix of level layout and enemy positioning anticipation. You wanna go to a place that will leave you protected, whether that means decent cover or fewer enemy presence. Causing distractions also helps (tossing a grenade to

the other side of the map can make people flock to that location and gain you another dozen seconds perhaps). Mental gameplay / mind games, etc.

You'll notice a trend here. They all involve a large amount of mental gameplay in which you have to try and outwit the other players. Learning to become GOOD at this mental gameplay at the same time that you learn to effectively control your character (precision shooting, dodging, etc.) is what makes it fun to try and master (both are very hard things to do). You'll want something that combines the gameplay skill players have (controlling their avatar) with their tactical/strategic skill (manipulating player coordination).

You'll notice that traditional sports won't necessarily depend on "scheming" quite as much due to the open layout of the "map" and how everyone can basically see each other. However, the small map also means that players can change the significance of their position much more quickly (moving the same amount of space results in a larger tactical difference due to the relative size of the play space). This means that there is a spectrum of reliance on control vs. mind gaming that your level design will evoke. Just another thing to take into account.

2) Cool game modes, some of which are found in real sports

- Gameplay revolves around unique rules regarding the manipulation of a portable object (ball, puck, etc.). Actual points can only be scored by manipulating the object effectively, not by "beating" the opponents. E.g. football, hockey

- Gameplay revolves around defeating opponents within a unique set of conditions, e.g. ancient chariot racing combat, CoD's "Gun Game" (a personal favorite where everyone proceeds through the same sequence of weapons, moving to the next loadout with each kill, trying to get to the end. Ideally the last gun is very hard to get a kill with. Only a good idea if you have many varied and interesting weapons).

- Gameplay revolves around 1 player in particular being in a unique condition, e.g. Halo's Juggernaut (which I always thought was really fun). Many variations.

- Gameplay revolves around one team having a unique condition compared to the other team (Halo's Infection - one side with long-range, but limited ammo weapons, the other with insta-kill, short-range, limitless ammo weapons). Many variations.

Even these give you tons of crazy options. Imagine something where players must deliver a neutral bomb from one end of the map to the other. It's an open plain with some occasional visually blocking structures. Everyone is invisible with a sniper rifle. The player who picks up the bomb becomes visible and must exit a tunnel where players are free to take shots at him. However, he is also now super fast and bounces of surfaces like crazy. Perhaps he can dodge his way to the other side? Plus, anyone who shoots him may get spotted by the snipers on YOUR team and end up counter-sniped. There are more changes you could make to that scenario to make it even more tactically/strategically interesting.

Bottom line, devise something you can implement, test, and iterate on to "find the fun" that involves precision motor skills and visual tracking (you said it's an FPS, right?) as well as some sort of mental gameplay that is going on behind the scenes to spice up the experience.