Rainbow Six Siege is a team-based 5 vs 5 shooter with asymmetrical game-play. One team has the role of Attack and the other plays Defence. The choice of 'Operators' differs with these roles. Operators are the characters you play as which have different guns and gadgets, gearing them towards a specific role in the team. One example is the Medic Operator who has a pistol and shotgun, with a deployable shield and a gun that can heal team-mates. He can attack just fine, but has more of a supportive role. He is only available to the Defending team.
Your health does not regenerate so can only be restored if your team has the Medic. You only have one life, but can become injured which gives you the opportunity of being revived to 50% health if a team-mate comes to rescue you in time. This system places an importance of survival, meaning you need to be more methodical when engaging enemies.
It's important to make use of cover, move slowly to not draw attention to yourself, and stick with your team-mates. The various gadgets the operators have mix up the game-play since you need to keep an eye out for various traps.
The environments have a wide range of destructible scenery. Some objects cannot be destroyed at all, some can be partially shot to give you hole to shoot through, and others can be destroyed to give you an entry point to walk through. Since walls can be shot through, you must always keep alert and not assume you are safe. Simple wooden barricades can be destroyed with 3 mêlée attacks, whilst stronger fortifications require explosives, or Operator Sledge's hammer.
It's wise to play with the sound at a high volume so you can take advantage of sound cues. Footsteps will alert you to danger, and you could place barbed wire at strategic locations to be alerted to the rustling sound when players pass through it. Gunshots and explosions will give you a huge clue where the action is, although crafty players could use sound as a distraction and blow up a wall, but charge in at the opposite side.
There's multiple match types which take place over several maps. Within these maps, the objective locations are randomised, and the different times of day and weather conditions can help mix up the game-play and keep things fresh.
Apart from the tutorial missions known as 'Situations', the game is online-multiplayer only. The Situations have three difficulty options and three optional objectives; giving you an incentive to play through them multiple times.
As far as the main online modes go, there is the normal 5 vs 5 mode, and a mode called Terrorist Hunt which is 5 humans versus numerous AI controlled Terrorists. With the normal multiplayer mode, you only have the option of the casual unranked mode until you reach Level 20.
The player-vs-player modes consist of five rounds with teams alternating between defending and attacking which involves diffusing a bomb or rescuing a hostage. In the initial phase, the defenders set up their barricades, while the attackers use remote-controlled drones for reconnaissance. Once the round starts, you can then engage. The team who wins three out of five rounds are the victors.
In addition to XP which levels you up, you also earn Renown which is used as in-game currency to unlock Operators and cosmetic changes for them. It's important to unlock a variety of Operators for both the Defence and Offence because two people cannot choose the same Operator. If you are left with none to choose from, then you get the generic Recruit. There will be a few times early on when this happens, but once you have levelled up a few times, you should have enough Renown to purchase a decent selection.
The game is pretty fun to play with random people but is the type of game where it is best to form a party of your own friends, with everyone communicating with headsets. That way, you can plan and execute effective strategies, rather than everyone doing their own thing. Personally, I found a lot of fun in the Terrorist Hunt mode, teaming up with random strangers to take down the AI controlled opponents. The casual ranked mode against other human players was a bit mixed. Often, I was defeated within minutes, meaning I end up just watching the rest of the game.