How difficult is it to make a new game mode?

[WiddaArcher]

I am not familiar with mapping at all and I am just curious as to how one could make a new game mode. This is not referring to new assets, server plugins, or mods. I am focusing on the logic of the objects involved in the map, which could create a gimmick map or a new game mode.

For example, could elements from different game modes be combined and how could a HUD interface be arranged for a new mode. Could I make a center control point spawn a neutral CTF Intel? Could I make a control point determine who has control of a neutral payload? Can I make the Intel a bomb that explodes the carrier and nearby players when it gets reset by a control point? Can I make a payload be pushed only by collecting beer/souls? Can I make multiple points where an Intel must be delivered each? Can I make a control point/payload require Intel to be captured, similar to Special Delivery. Are these concepts easy to make, or are they avoided because they over complicate the gameplay? I'd like to believe that these are simple enough that it only requires the map's I/O and SmartEdit stuff.

I am aware that I as a beginner I should not delve into new territory, and start with the basic modes, like a KOTH map, but as a potential long term goal I would like to make unique game modes and maybe even a new Halloween Boss. I really enjoy playing Player Destruction and Robot Destruction, and I hope that more game modes are made for this game. So as I look into the Hammer Dev Wiki stuff I'd like to know how custom game modes are made and how this community approaches new game modes.

 

[Fragancia]

For example, could elements from different game modes be combined and how could a HUD interface be arranged for a new mode. Could I make a center control point spawn a neutral CTF Intel? Could I make a control point determine who has control of a neutral payload? Can I make the Intel a bomb that explodes the carrier and nearby players when it gets reset by a control point? Can I make a payload be pushed only by collecting beer/souls? Can I make multiple points where an Intel must be delivered each? Can I make a control point/payload require Intel to be captured, similar to Special Delivery. Are these concepts easy to make, or are they avoided because they over complicate the gameplay? I'd like to believe that these are simple enough that it only requires the map's I/O and SmartEdit stuff.

I am aware that I as a beginner I should not delve into new territory, and start with the basic modes, like a KOTH map, but as a potential long term goal I would like to make unique game modes and maybe even a new Halloween Boss. I really enjoy playing Player Destruction and Robot Destruction, and I hope that more game modes are made for this game.

You are very limited in what you can do, you could try playing around with whatever gamemode entities exist but you may run into game breaking problems you can't fix and also may not work as well you might have hoped.
You cannot make a custom HUD for the map or change the existing HUD beyond what the gamemode entities allow you too.

TF2 doesn't have things like Vscripts which newer Valve made source games have like CS:GO, L4D2 and Portal 2 which could help out mapping enthusiasts a bit more in the making of custom gamemodes and mapping in general.
Making new bosses for Halloween is pretty much out of the question, you'll need the help of the TF Team for that.

 

[Crrrrrrystal]

The world editor, Hammer, is much more powerful than a lot people realize, it just takes a LOT of reading of the Valve Developer Wiki to make full use of its features. I don't know about a new Halloween boss, but some of the more creative and technical user have made some amazing things with it.
As you said, you need to get good first before getting into this new stuff. Though, the main reason that most people don't go making new game modes all the time is not necessarily because of the technical difficulty behind it, but the theoretical difficulty. Simply put, to make an entirely new game mode, you don't have any maps to look at to see how past maps have made your game mode balanced, you're all an your own. Everything on your new game map will have to be entirely your own, and it has to be even more fun than most maps because many users will have a sour "new things are bad" attitude coming in. Of course, once you've made many many other maps, perhaps you will be good enough to know how to balance something that massive all on your own.

There's only one way to find out, right?

 

[Egan]

Yeah, so you can do those things that you listed, but as mentioned by both @Fragancia and @Crrrrrrystal it probably will be a lot of work to get it running, and then to 'feel around' if it's balanced/working in gameplay afterwards.

The most useful things to know for TF2 hammer entity IO would be of course the IO system, so check Tophattwaffle's tutorial on that, since he goes over a ton of detail about it; and then also know that if you click the Entity Panel's Help button that it opens up all the documented (by Valve) Keyvalues, Inputs, and Outputs for that entity, with descriptions of what it does, and what kind of value the outputs 'pass' to other entity inputs.

 

[Yabayabayaba]

no custom gamemode will be easy, but for each idea

center control point spawn a neutral CTF Intel

Pretty easy, I have done something similar with ctf_mailcar. Without the moving elements it would work pretty well (attaching a flag to a moving train is the bane of my existence)

Could I make a control point determine who has control of a neutral payload

Harder, and getting into advanced I/O, but totally possible

Can I make the Intel a bomb that explodes the carrier and nearby players when it gets reset by a control point

This sounds soo fun that I might use it, but yes this is possible and barring issues getting the intel to disappear without a timer when exploded, not terrably hard. Would require knowledge of parenting, so harder than the first one.

Can I make a payload be pushed only by collecting beer/souls

Like pushing the cart takes a soul per second? parenting a capture zone to the payload instead of the normal one would produce this affect

Can I make multiple points where an Intel must be delivered each

Have tried something like this, and this has several related prefabs. This isn't terribly hard, but a large I/O system will likely be hard to make/troubleshoot

Can I make a control point/payload require Intel to be captured, similar to Special Delivery

Very easily, by using a filter

Most of these ideas arn't that over complicated, and some I am likely to try now. If you do a bit of research on the I/O system you might find designing complicated events and logic to be fun. Bosses can be made in game with I/O (likely using track trains), but that is a whole new ball park, especially if you want a roaming one like the HHH. If you want help I would be happy to give you advice and perhaps make prefabs if desired.