Review: Chain Reaction 2018

It looks like 2019 is going to be a year of solitaire play, with short sessions snatched between discharging other responsibilities; that usually turns me back towards the Two Hour Wargames stable, as those products are fast, easy to use, and focused on telling a story about your solo hero and his companions.

In a Nutshell: The latest iteration of the core ruleset from Two Hour Wargames, 21 page PDF, free to download. Its purpose is to let you try out the core rules before you buy one of the more elaborate games with some setting and campaign rules.

As usual for THW, the format is very basic; two-column black on white text with the odd illustration and a colour cover. The 2018 version includes the battle board and counters from 5150 No Limits Maiden Voyage so you can start playing as soon as you have printed and cut out the counters.

Changes from Earlier Editions

The THW game engine was remarkably stable over a decade or more, but now some major changes are being introduced.

First, the movement rules. Like other recent THW products, these are no longer focused on figures moving across a 4′ x 4′ table, but are abstracted onto an 8″ x 10″ area called a battle board. This means the turn sequence has also been rewritten.

Second, the various tables for In Sight, Man Down and other reactions have been collapsed into a single Will to Fight table.

Third, shooting is now a simple check against the figure’s Rep, rather than the previous 1d6 + Rep + tactical modifiers.

Overall, the game is faster, simpler, easier to learn – but less tactically rich. (THW games divided some years ago into those aimed at roleplayers, and those intended for skirmish wargamers; so it’s possible that the skirmish wargames ones have retained movement and tactics, but I haven’t investigated that.)


As the player, you control one ‘Star’, which most games would call a Player Character. By default, this person starts with Rep 5 and three advantages over NPCs or ‘Grunts’: Star Power, which lets you soak damage; Extraordinary Effort, which lets you roll an extra die once per encounter; and Free Will, which lets you decide whether you and your companions will disengage from combat – Grunts without a Star to lead them are at the mercy of the dice. Grunts also typically have lower Reps, usually 3 or 4 but sometimes 5.

Each figure also has a Class (Citizen, Ganger, Mercenary, Military or Police) and an associated Attribute which affects how it plays in combat – police, for example, are always the last to leave the battle board. The full products have a wider range of Classes and a much wider range of Attributes.

Your group can be no larger than your Rep, usually your Star and up to four Grunts. The opposition ranges from two fewer than your band to two more.

Sometimes the free demo rules from THW have rules for increasing or decreasing your Rep by experience, and sometimes they don’t. This set doesn’t.


There are three standard encounters provided; confrontation, defend, and raid, with a quick method for determining who you are fighting and tables of pregenerated opponents. The full rules and setting books usually have over a dozen encounters, and campaign rules to tie them together into an ongoing story. Each encounter type has special instructions that modify the basic rules.

I should also mention PEFs – Possible Enemy Forces – which in earlier editions wandered around the tabletop, but are now resolved one after the other with no manoeuvring to chase or avoid them. As usual, resolving a PEF might mean you encounter enemy forces, increase the chances of doing so later, or be a false alarm.

The core of the game is resolving firefights, so let’s look at the turn sequence for that.

  • Determine which side has advantage. This is random; the side with advantage begins the fight in cover, except at night when both sides are in cover.
  • Leaders now roll off against their Rep; winner goes first, draws go to the side with advantage.
  • Each figure on the active side may now shoot, melee, recover from duck back, or leave the battle board.
  • Both sides now take a Will to Fight check, which may mean that one or more figures involuntarily leave the board.
  • The other side now becomes active, and we repeat the above two steps.
  • When at least one side has completely left the board, the encounter is over.

Shooting: At least one figure on the active side must shoot at each figure on the inactive side. If they have any figures left over, they can start doubling up. Figures able to shoot more than once per turn may shoot multiple opponents. If you are hit, you roll vs Rep to see if you are killed, incapacitated, or duck back into cover. There are no wound levels here; if you get hit by a bullet, you’re going down.

Melee: When you charge into melee, the defender gets a chance to shoot you, and if you make it into combat, you roll against your Rep to see if one side or both is incapacitated or has their Rep temporarily reduced (it’s restored at the end of the melee).


This does what it sets out to do; it explains how the core rules work so you can decide whether they are for you, or not. There are some discrepancies between the rules themselves and the examples; in these cases I think the examples are correct. However, I have a better understanding of the combat rules from reading this a couple of times than I acquired by actually playing Maiden Voyage for some weeks.

While earlier THW products were designed as tabletop wargames for head to head, same side, or solitaire play as either wargames or light roleplaying games, I’d say the current crop are designed as abstract solitaire roleplaying games first and foremost. That makes them well suited for my purposes, but I can’t help feeling they’ve lost something as a result. The loss of all tactical movement and associated rules makes it much faster and simpler, but largely eliminates player decisions, which in my opinion makes it less suitable for group play.

How much faster? Previous editions aimed to complete an encounter in no more than two hours, and it often took me longer than that. Current rules make an encounter in 30 minutes entirely plausible, and I have yet to go over that limit.

Notice though that this has been achieved by dropping the reaction system which gave the game its name in favour of an IGO-UGO turn sequence.

If you want the old way back, go for the 2015 version of Chain Reaction, which is still available. I warn you though, the “AI” built into the reaction tables is ruthless and punishes poor tactics ruthlessly.

Overall Rating: 4 out of 5, but still a lot of game for the money.

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