Adventure Race Styles
There are a few different common race styles out there that you're likely to see. In order to avoid confusion about the terms, I go over their differences on this page. These are independent of race length and sometimes races make use of a combination of different styles.
The classic style of adventure racing is by far the most common for races today. This is one of the more structured ways to host a race. Typically in this style, the legs of the race are laid out in a specific order, each having a certain number of checkpoints. Competitors will do the race legs in order until they either finish the course or the race cutoff occurs. There are no intermediate time cutoffs, and slower teams may not get to do all of the stages of the race, for example there may be a trekking section toward the end which only the top teams will end up doing.
In most legs of the race, the checkpoints must be gotten in a specific order, though often there are individual sections of the race which are themselves Score-O style (see below). Specifically the first stage of a race is commonly Score-O style since that helps to spread out teams rather than sending everyone off to the same checkpoint at the same time. Another thing to note about classic style is that usually there are not penalties for skipping checkpoints (other than not getting the point). In a race in which your team expects to not be able to clear the course, it can be an excellent idea to skip the most time-consuming checkpoints early in the race so that you have time to pick up any easier points in later stages that you might not have gotten to. So despite the structured nature of the race, there are still opportunities for many strategic decisions.
As with each style, there are pros and cons to the classic style of adventure racing. A major positive for racers is that it actually feels like a real race against other teams. Since all racers are traveling through the segments of the course in the same order, you will often trade places with certain teams and will usually be able to tell what place you are in (although there is always the possibility that you or your competition skipped checkpoints so you may not know exactly if a team that passes you is still ahead of you in points). This can lead to some bantering with the other teams which is always a fun part of racing. Also because race directors know beforehand the order you will do each event in, it gives them the power to lay the race out in a logical manner, putting the most fun segments early in the race so that all teams will get to experience them. This is also the best style for spectators because they will know where most teams are on the course.
A possible negative of the classic style of adventure racing, depending on your viewpoint, is that it forces each team to do events that they might not be good at or like to do before moving on to the rest of the race. My personal bias in the matter is that this is not much of a negative because part of the beauty of adventure racing is that you are taken out of your comfort zone and made to do things that you wouldn't ordinarily do, which can often lead to glorious moments that you never would have experienced otherwise. Another negative of the classic style is that early in the race, teams tend to be quite bunched up which can lead to a lot of confusion (or worse - teams might simply follow other teams rather than navigating on their own).
This is a problem that is easily managed by a good race director though, as often they will purposefully design the first section of the course so as to split up teams as much as possible. I've seen this done in several ways. One common strategy is to start the race with a short orienteering section on foot where competitors can get the checkpoints in any order (Score-O style). This will automatically spread teams out because there will be many different route choices. Some directors choose more whimsical approaches. One has had each team pick one member to give up a shoe prior to the race. The race then started with the rest of the team having to find the missing shoe which was hidden on the property somewhere before going out on the first real section of the race!
Score-O or Rogaine Style
I know I know, many of you are probably thinking I'm making some reference to the popular men's hair product. Actually Rogaining is a sport that significantly predated the hair product. Basically a Rogaine is a long team orienteering competition where competitors can get checkpoints in any order. A Score-O is essentially the same thing, but often individual instead of team and significantly shorter. So all it means to say that an adventure race is Score-O style or Rogaine style is that you can get the checkpoints in any order.
Often races will have segments which are in themselves Score-O style, but it is less common for an entire race to be Score-O style. There are some races though that are organized this way. Usually the way they work is that you will get all the information for the entire race at or before the start of the race, and there will be multiple loops which will all start and finish at the same spot (TA). Maybe there will be a biking loop, a trekking loop, and a paddling loop for example. The race will often be set up so that it's not possible to clear the course before the cutoff time. As a team, you'll have to decide how you want to split up your time. You might base this on which discipline is your strength or which segment looks like the most fun and choose to spend more time picking up checkpoints on that segment. For example, if you are strong bikers, you might start out with the biking section and try to clear all of the checkpoints from that, then use the remaining time to pick out the easier points from the trekking and/or paddling sections.
Note that it is common for checkpoints in Score-O style races to be worth different point values based on how hard they are to find or how close they are to the TA. If a checkpoint that is 15 minutes away from the start is worth 1 point, then the checkpoints out on the fringes of the map might be worth 3 or 4.
An advantage of Rogaine-style adventure racing is that teams have a lot of flexibility in deciding which checkpoints to go for. This actually adds an element of race strategy which might help even out the athletic potential of the teams in the race, because a team that is weak in one discipline but has a really strong strategy about which checkpoints to go for and in what order may be able to overcome their athletic disadvantages and place really well. Also teams can even tailor which checkpoints they go for in each section to their specific strengths and weaknesses. For example, some people are fast runners on flat trails but slow down dramatically when off-trail and climbing or descending. Or on the flip side, some racers are strong hikers and do just fine off-trail and in hilly terrain, but don't speed up much when on flat trails. In a Score-O style race, each team can go after the checkpoints that mesh with their strengths.
One disadvantage of Score-O or Rogaine style racing is that it is impossible to know how you are doing in the race with respect to other teams until the race is over. This will bother some people more than others. Many racers are out there to have a good time and do their best, other teams be damned. And that's a good attitude to have. But there will also be some teams which are highly competitive and for them the race experience might not be as fun in a Score-O style race without having other teams pressuring them to excel. There's really no "passing" or being passed in this style because the team that you're going by might have twice as many points as you already.
Expedition style adventure racing is the most extreme style of race which puts the most strain on the competitors. It's also probably the style truest to the intentions of the original adventure races, most of which were point-to-point type affairs. In a true expedition style race, teams will start the race with everything they will need for the whole race on their backs and travel through the entire course without a chance to resupply. Yes that means racers could be carrying paddles, PFDs, and climbing gear for the entire race! Sometimes such races are point-to-point deals in which the race finish will be many miles away from the start. Alternately the race can take the form of one big loop eventually taking competitors back to where they started.
Expedition style adventure races have pros and cons like any other style, but a lot will depend on your point of view. For some, the biggest positive is that racers must truly be as prepared and self-sufficient as if they were going out on an expedition in unknown territory, while others will consider this a negative aspect. Either way, one definite downside of expedition races is that they make it very difficult or boring to be a spectator of the race. While adventure racing in general is not the best spectator sport, expedition style races sometimes make it hard to even figure out what county a team might be in at any given point.
Note that there is a difference between "expedition style" races and "expedition races"- a term which is actually more about length than style. Most long races today are called expedition races simply on account of their length (3+ days long) but they're usually not strictly "expedition style" (most expedition length races are "classic-style" as described above) because teams will have several chances to get to their gear and refuel on food and water. An expedition style race can actually be as long or short as any other race, and it's not rare to find sprint races that are expedition style.
Urban Adventure Races
Urban adventure races are gaining in popularity over the last few years. These can maybe be considered a sub-style under sprint races as they are usually fairly short in length and very casual. Often the majority of teams in an urban race may be doing it just for fun rather than for serious competition because they will have more special challenges and fun activities than more wilderness based races, due to the extra options available to a race director in an urban area.
For example in various urban races I've heard of race directors leading teams into a bar to chug a beer (or soft drink, if not alcoholically inclined), having teams kick a field goal at a football field, play miniature golf, or do a lot of other things that you might not associate with a serious athletic competition. Also navigation will usually be more street based in an urban race for obvious reasons. Topo maps may not even be necessary as it will be more important to turn at the right street than read the terrain features of the land. Biking will be most if not all on streets. Urban races are great for a beginning racer to get a feel for the sport or just any racer who wants to relax a little and have some fun!
Stage races are sort of a blurring of the boundary between adventure racing and more traditional events. In a stage race, segments are broken up by a mandatory rest period. The most common configuration has racers doing one stage a day and resting overnight before competing in the next stage. Often these are 3 or 4 day competitions. Stage races can be extremely challenging physically, but obviously lack some of the "adventure" aspect of an adventure race because racers will have the option of sleeping in real beds and eating out for dinner. Also usually there is no racing in the dark. Some stage races are closer in the continuum to true adventure racing than others, but many allow for athletes with a more limited skill set to compete. They may have limited or no navigation aspect. Also, stage races often allow individual competitors rather than requiring teams.