Track and Field (in tower defense)

I've been thinking lately about TD games, of which by far my favorite (just to lay my biases out up front) are the Bloons TD games. Not least of which because they're nonviolent, unlike 99% of TD games, which are basically built around methodical mass murder.

But the Bloons games are all track-based TD games. Sometimes there's more than one path, and occasionally a path has a branch point, but basically the bloons are all on a track and you know where they're going to go. And, with a few rare exceptions, you can't build a tower on this track, so as to physically block them.

​

This contrasts quite a lot with "open field" TD games, where there is no track; creeps are just trying to get from one side of the screen to the other, and you can physically block them with your towers. I've tried a few of these, and didn't like them much, but I can't put my finger on exactly why.

​

So. Game design question for the group: how does this decision (open field vs. track) fundamentally change the fun factor? And (for bonus points!), are there other types of games where you could apply a track to a previously open field, or vice versa, to make a very different variant on the design?

Cheers,
- Joe

P.S. And yeah, then there are multi-track TD games like Plants vs. Zombies, which are sort of in between. But let' s not muddy the waters too much just yet.

 

Tower defence games are all about optimising the type and placement of towers. Take bloons for example. You place towers that can pop lead balloons near the start. You combine freeze monkeys with cannons. You aim mortars on natural bottle necks.

With a track all sorts of interesting things exist. Long straights where a tower with piercing does well. Loops where a AOE does well. In short you have interesting decisions.

An open field gives you none of this. It's basically a dps gate. Dps gates are no fun.

Now a field with a series of dynamic obstacles, that could offer interesting choices.

 

Plants vs. Zombies is a lot closer to open field than track based game. Other than garlic the obstacles don't route the zombies and I don't think I'm alone in thinking the game is fun.

 

I nearly decided to like Plants vs Zombies.

Yes, that is a recommendation. Relatively speaking.

 

Plants versus zombies has some other elements that make it fun. As well as not being a traditional open field game. The zombies follow defined paths, so you can set up strategies and combos knowing the enemies won't just go around them.

The other thing it has going for it is that it's more of an action game then a traditional tower defense game. Sure there is plenty if strategy. But in the final show down your ability to collect resources, replace towers, and place bombs quickly also matters a lot.

 

Is it? I've only played the first, but I could have sworn it was four or five linear tracks, which happen to all be adjacent. It looks like an open field, but it doesn't typically behave like one.

As far as I can tell the main difference between "track" and "field" type TD games is that in a track you have less/no control over the enemy movement and a fair amount of information about where they'll go, where in a field game you have significant control over their movement but otherwise little or no information about where they'll go.

To me there's two things. First up, the player makes different types of decisions in each as described above - in one it's about optimisation of one thing a-la @BoredMoremon's description, where in the other it's about balancing control of multiple.

Secondly, and possibly more importantly, I've always found level design of track type games to be more interesting. An open field is an open field. There's limits as to what kind of interesting level you can design when it has to be flat and open, so most of the differences from level to level are about what kind of enemies there are and what abilities the player has. A track game, on the other hand, has a whole other dimension of creativity at its disposal - the track can do interesting things like have different shapes, restrict the placement or usefulness of different types of towers, or make particular types or combinations of enemies particularly strong or weak.

 

Thanks guys. It's a bit funny, because I saw a bunch of open-field TD games in the store recently that were bragging about their open-field-ness like it was a good thing. Sounds like I'm not alone in finding more play value in the track-based games!

 

I think open field games are a more difficult design to make interesting. The player is left to create a 'maze' of DPS, which means they're basically the level designer and YOU are the one who has to create the enemies that will actively try to poke holes in their design. I think that's where most of the open TD games fail, the enemies are just lemmings thrown into the DPS maze. In order to make it interesting the enemies would have to have some kind of AI or behavior pattern... but it can't be random, because the fun is in finding an optimal way to defend against each pattern or method.

Maybe more important is the question of "active vs. passive" - Do you do anything after you hit "go" and how much? An open TD game may be better suited to a more active play style.

Then, and lastly, there's some examples that are kind of hybrids - where there is a set path but the path is very wide and you can build in it. The Armor Games success (the title of which I have forgotten at the moment) was an example of this, and you can see how their very "active" play style tied into it. Some googling and I am sure you can find the one I am talking about

 

I much prefer open field TD games, the strategy factor goes way up and you can still basically create a single-path style TD game through level design so the depth of the game goes up significantly by supporting open field option versus path-only.

 

In the end, either can work. As with any game, it's about providing gamers with meaningful choices and a variety of options. The biggest boredom factor that comes from most tower defenses is the generic nature of the towers. In Plants vs. Zombies, you have at least 20 unique effects in addition to the instant gratification behind how you collect resources. You can eat zombies, magnetize their tools, catapult over big ones, slow them down, drop single-use explosives, etc.

Track or field, if you provide enemy and turret variety with meaningfully different effects, it'll be a good game.

 

There's the towers and there's also the enemy behaviours. The thing is that in a "track"-style game the designers have far more control over how to make interesting and meaningful interactions between those things than they do in a "field" -style game. Done well either can work, I simply suspect that one is easier to do well than the other.

 

The poster I responded to seem to be talking about open field as in just those games where you move left-to-right (else why say "Now a field with a series of dynamic obstacles, that could offer interesting choices." as if it was a special case). Given I was responding directly to them I figured it best to use their terminology.

My real point was that you can have interesting games with many configurations, simply moving left to right, tracks, open-fields (basically what @GargerathSunman elaborates on above).